■w
ss ' /// > Jy ■ c> v s . >
1- * ri
"o $
■*.<* .-
^ ^. '
**
%
V *>
•#N
, ^ V^
ClV
^ v^
V •♦
\V V » 0 7 ^ ^^
</-
tl
- .
,0o.
^ X
a> ^
-
I), = ■■.
^ >
'^^
^
LABORATORY MANUAL
OF
Inorganic Preparations
H. T. VULTE, PH. D., F. C S.
INSTRUCTOR IN CHEMISTRY, COLUMBIA UNIVERSITY, AND LECTURER IN-
DOMESTIC SCIENCE, TEACHERS' COLLEGE, N. Y.
AND
GEORGE M S. NEUSTADT
INSTRUCTOR IN CHEMICAL ANALYSIS, COOPER UNION. N. Y.
THIRD EDITION
NEW YORK
GEO. GOTTSBERGER PECK, Publisher
117 CHAMBERS STREET
I902
THE LIBRARY ®F
CONGRESS,
Two Copies Receive©
APR, If 1902
COPYWSHT SNTRV
CLASS CtOfXa No.
i o r-i i
COPY S. I
Entered according to Act of Congress, in the year i8qs,
By GEO. GOTTSBERGER PECK,
In the Office of the Librarian of Congress, at Washington, D. C.
Entered according to Act of Congress, in the year 1902,
Bv GEO. GOTTSBERGER PECK,
In the Office of the Librarian of Congress, at Washington, D. C.
PREFACE
The study of inorganic chemistry naturally precedes that of
organic, and in a certain way this plan is carried out in a com-
plete chemical course. The study of the organic branch, how-
ever, proceeds on a much more logical plan than that usually
adopted in inorganic work; one of the chief advantages being
the practice to which the student is introduced very early
in his course. The following work is synthetic, and shows
how compounds, often very complex in character, rare in occur-
rence or expensive in preparation, may be produced from simple
substances, or from those which are comparatively plenty and
cheap, and at the same time the bye products may be saved.
Such a course of study is also of great value in inorganic work, but
should precede and lead up to, and not follow organic chem-
istry. However, a contrary plan seems to have been followed,
for while we have various works on organic preparations, there
are none, so far as the authors know, in the inorganic branch
of the subject (at least not in English), excepting the works on
Elementary Chemistry; and where these treat of the subject in
laboratory practice, the methods are those which cannot be
recommended as the best and most economical.
In many laboratories the waste of material is greater than the
use. Students are apt to acquire the idea that after a certain re-
sult has been produced the rest of the material is worthless, and
in consequence much loss occurs from throwing away valuable
material which can be recovered or used with little trouble or
expense. It is not a very difficult operation to purify the various
commercial salts, converting them into C. P. reagents, and in the
operation the student cannot help acquiring facts which are
directly and forcibly brought to his knowledge. Too much reli-
ance is usually placed on the so-called C. P. chemicals in com-
mon use. Many are high-priced and apt to deteriorate in the
IV PREFACE.
packages. There is no reason why the student should not pre-
pare many of these, unless it be that he does not always know
where to look for the necessary information.
The book is designed to meet a long felt want in the inor-
ganic laboratory, in training the student to prepare his own
reagents and to test them for the customary impurities. The
methods are largely those in commercial use, and should prove
of value to those studying Applied Chemistry.
The works of Fresenius, Erdmann and others, as well as the
various chemical journals for some years past, have been carefully
searched, and such information as was thought valuable has been
collected and arranged in order, beginning with the simplest
operations and gradually increasing in difficulty as the student
acquires skill in his work. As far as possible, references to the
original articles have been given.
October, 1895.
PREFACE TO SECOND EDITION.
In this new edition, the number of small errors in the
first edition, almost unavoidable in such a case, have been
corrected, and a number of minor improvements have been
made. All suggestions for alterations which have reached us
since the publication of the first edition, have been carefully
considered, and wherever it was possible and consistent with
our endeavor to maintain unchanged the general scope and
character of the book, the changes have been made. The
favorable reception with which the first edition was received,
both by journals of acknowledged authority, and by chemists
of extended experience in this class of work, both in this
country and abroad, has shown that the work is not without
usefulness in the field for which it was designated.
THE AUTHORS.
Columbia University, 1897.
PREFACE TO THIRD EDITION.
In presenting the third edition of this work a number of
minor improvements have been made, and the part dealing with
volumetric analysis has been entirely rewritten. All suggestions
that have reached us since the publication of the second edition
have been considered and acted upon when thought advisable.
We beg to thank our numerous friends for the favorable
reception accorded the first two editions of this work, and trust
that this new edition will be as acceptable as the two former.
THE AUTHORS,
Columbia University, Feb.. 1902,
LABORATORY MANUAL
OF
INORGANIC PREPARATIONS,
WATER.
H20.
Pure water is obtained by distilling spring water from
a copper still with head and condenser made of pure
tin.* The distillation is carried to about three-fourths
of the quantity operated upon. If it is desired to have the
distilled water perfectly tree trom carbonic acid and am-
monium carbonate, the portions passing over first must be
rejected. In the larger chemical laboratories, distilled
water is obtained from the steam apparatus which serves
for drying, etc. Rain water collected in the open air may
in many cases be substituted for distilled water.
It must be colorless, odorless, and tasteless, and
should not leave the smallest residue when evaporated in a
platinum vessel. It should not be changed by ammonium
sulphide (copper, lead, iron), nor rendered turbid by baryta
water (carbonic acid). No cloudiness should be caused
even after long standing by the addition of ammonium
oxalate, of barium chloride and hydrochloric acid (sul-
* Glass retorts with ordinary condensers may be used when small
quantities of water are required.
2 LABORATORY MANUAL OF
phuric acid), of silver nitrate and nitric acid (chlorides), or
of mercuric chloride and sodium carbonate (ammonia).
We use water principally as a simple solvent for a great
variety of substances.
AMMONIUM— FREE WATER.
If the ordinary distilled water gives a reaction for am-
monia with Nessler's reagent, it should be treated with
sodium carbonate, about one gram to the litre, boiled until
one-fourth has been evaporated and then distilled.
Ammonium free water may also be prepared by dis-
tilling water made slightly acid with sulphuric acid.
WATER FREE FROM ORGANIC MATTER AND AMMONIA.*
About 15-20 litres of ordinary distilled water, to which
about 1 gram, of potassium hydrate and 0.2 gram, of
potassium permanganate have been added are maintained
at about iOO° C. for twenty-four hours under an inverted
condenser, after which the condenser is reversed and the
water distilled off, discarding the first portions. Apply
Nessler's test to the distillate from time to time, until 100
c.c. show no coloration and collect that which comes over
subsequently, stopping 500 c.c. short of dryness.
As an additional precaution the water thus obtained
may be acidified with sulphuric acid and re-distilled.
For preparing distilled water, the ordinary tin lined
copper still and block tin condenser may be used, or a
more economical way is to make use of the well known
Domestic Water Still, (Fig. 1). This piece of apparatus
* Water Analysis, Frankland, p. 113.
INORGANIC PREPARATIONS.
yields a good quality of product, with a minimum ex-
penditure of heat and condenser water, and is moreover
very compact.
Fig. l.
Water free from organic matter and ammonium, which
is indispensable in water analysis and the preparation of
many standard solutions such as potassium permanganate,
argentic nitrate etc., is best prepared in the apparatus
shown in. Fig 2, which consists of a glass-stoppered flask
with side-neck tube. The end of the side-neck tube is turned
vertically downward, being thrust deeply into the tin tube
of the condenser, and held in place there by a short piece of
rubber tubing. The three-eighth inch block tin pipe forming
the condenser-tube is bent zigzag instead of in the conven-
LABORATORY MANUAL OF
tional helix. This affords a more even flow of the distillate.
The cylindrical copper jacket containing the water for cool-
ing is about four inches in diameter, and fifteen inches long.
The disk closing the lower end is arched upward so that in
Fig. 2.
case the condenser " sweats " from the use of very cold
water, the drip from the outside can not contaminate the
distillate. The lower end of the tin tube is cut aslant for
the more certain delivery of the distillate.
INORGANIC PREPARATIONS.
ETHYL ALCOHOL.
C2H5.OH.
Two sorts of alcohol are used in chemical analy-
sis, viz. : 1st, Commercial " 95 per cent, alcohol,"
which really contains 93 to 94 per cent, of alcohol
by weight ; and 2d, absolute alcohol. The latter may be
prepared most conveniently by placing in a flask or tin can
800 grams of good quick-lime in coarse powder or small
lumps, adding 1 litre of" 95 per cent, alcohol," connecting
the vessel with the lower end of a Liebig condenser, and
keeping its contents boiling on a water bath for an hour.
The can is then connected to the upper end of a dry conden-
ser, and the dehydrated alcohol distilled off into a bottle
for use.*
Pure alcohol must completely volatilize, and ought
not to leave a smell of fusel-oil when rubbed between
the hands ; nor should it alter the color of moist blue or
red litmus paper. When kindled, it must burn with a faint
bluish, barely preceptible flame.
Commercial Alcohol invariably contains aldehyde and
if kept in tin cans stannic oxide as well; such alcohol can-
not be used for the preparation of alcoholic potash solutions,
argentic nitrate or for Hiibl's iodo-mercuric chloride
solution. For such purposes either of the two following
methods may be used.
A convenient amount of the alcohol to be purified is
shaken with pulverized potassium permanganate until it
assumes a decided color. It is then allowed to stand for
* Erlenmeyer ; J. Lawrence Smith.
6 LABORATORY MANUAL OF
some hours, until the permanganate has been decomposed
and brown manganese oxide is deposited. A pinch of
pulverized calcium carbonate is then added, and the alcohol
distilled at the rate of about 50 c. c. in 20 minutes from
a flask provided with a Wurtz tube or one of the Lebel-
Heninger pattern. The distillate is tested frequently until
about ioc. c. thereof, when boiled with 1 c. c. of strong
(syrup) solution of caustic soda or potash, gives no percept-
ible yellow coloration on standing for 20 minutes or half
an hour. What distills over after that time is preserved for
use.
The first distillates may be added to the small amount
remaining in the distilling flask (which should not be driven
down to the complete dryness), and a fresh portion of puri-
fied alcohol recovered.
The rationale of the proceeding appears to be that the
permanganate oxidizes and destroys chiefly the fusel- oil,
furfurol and other compounds of that nature, the acids
resulting from the reaction are neutralized by the calcium
carbonate added before distillation, and by distilling
slowly the aldehyde at least is concentrated in the first
portions of the distillate. Distillation of alcohol contain-
ing caustic potash or soda seemed to cause a constant
formation of aldehyde. The alcohol thus purified is per-
fectly neutral, and gives most satisfactory results when
used as a solvent for caustic alkalies or silver nitrate, the
solutions remaining as colorless as distilled water, even
after boiling and standing indefinitely, if properly pro-
tected from dust and other external influences.*
Jour. Am. Chem. Soc. — E. Waller.
INORGANIC PREPARATIONS.
The second method consists in distilling the alcohol
with some caustic potash in the presence of a large quantity
of non-volatile fatty acid ; either oleic or stearic is gener-
ally used, the process is simple and the result good.
OXYGEN.
02.
The compressed gas put up in steel cylinders is
sufficiently pure for most purposes, but when not avail-
able the gas maybe readily prepared by heating a mixture
of equal parts of potassium chlorate and manganese di-
oxide, in a copper retort, or better, in an apparatus similar
to fig. 3.
UM 3
Fig. 3.
Oxygen gas made in this way is liable to contain
chlorine or oxides of chlorine and carbon dioxide, it is
purified by washing with potassium hydrate and dried by
passing through concentrated sulphuric acid.
Oxygen may also be prepared by treating sodium
dioxide Na302 with dilute acid, either hydrochloric or
sulphuric.
8 LABORATORY MANUAL OF
Na202 f 2HC1 = O + 2NaCl + HgO,
great heat is evolved in this reaction and the operation
must be conducted with care; it is however an excellent way
to oxidize solutions, in which case the solution is made acid
and the sodium dioxide dropped in and well stirred until
the desired effect has been produced.
In the wet way oxygen is produced by treating
"Chloride of Lime " Ca(C10)2,CaCl3 in disc form, in a Kipp's
Apparatus with a mixture of I litre of hydrogen dioxide and
53 c. c. nitric acid com. Sp. Gr. 1.265. The same pre-
cautions for purification are necessary as in the case of
manganese dioxide and potassium chlorate.
To prepare oxygen, cubes consisting of a mixture of
2 parts of barium dioxide, 1 part of manganese dioxide
and 1 part of plaster are used with hydrochloric acid (sp.
gr. 1. 12) diluted with an equal volume of water. The oxy-
gen evolved contains traces of chlorine and must there-
fore be washed with an alkali*
It can also be prepared by adding potassium perman-
ganate to hydrogen peroxide made alkaline with ammonia. t
Oxygen is a colorless gas, and without odor. It is
liquified with difficulty, requiring a pressure of 320 atmos-
pheres at 212° F. Oxygen is remarkable for the wide
range of its chemical attraction for other elementary bodies
with all of which it is capable of entering into combi-
nation except one, namely fluorine.
* G. Neumann, Ber. 20, 1584.
f C. F. Gohring, Chem. Zeit. 12, 1659.
INORGANIC PREPARATIONS.
HYDROGEN.
H2.
Hydrogen is best prepared from granulated zinc
and dilute sulphuric acid (i litre acid, 5 litres water) in
Kipp's Apparatus ; the zinc should not be too pure or the
supply of gas will be slow and feeble. In any case it is well
to add a small amount of copper sulphate solution, just
sufficient to produce a thin coat of copper on the zinc, oi
a piece of platinum foil maybe used in place of the copper
sulphate ; in this latter case it is better to amalgamate the
zinc, by first treating with dilute sulphuric acid and then
adding mercury and shaking, or by simply treating the
zinc with a strong solution of mercuric nitrate containing
free nitric acid.
A granulated alloy of tin and zinc, containing about 83
per cent, of the latter, prepared by adding zinc to molten
tin as long as it dissolves, is recommended for use in
Kipp's apparatus. The pieces retain their shape and size
after all the zinc is dissolved out, and therefore have no
tendency to fall through into the lower bulb.*
Hydrogen may also be prepared by sodium amalgam
with dilute acids.
Hydrogen gas prepared by the action of zinc and acid
is never pure, but may contain hydrocarbons, hydrogen
sulphide, sulphur dioxide, etc.
The very small amount of arsenic generally present,
as AsH3, may be neglected. The other impurities are re-
moved by first passing the gas through a solution of
* J. Habermann, Zeit. Anal. Chem. 28,
IO LABORATORY MANUAL OF
potassium permanganate in order to oxidize hydrocarbons,
hydrogen sulphide, etc., then through solution of potassium
hydrate to absorb carbon dioxide, sulphur dioxide, etc.,
and finally through concentrated sulphuric acid and calcium
chloride to remove water.
Hydrogen is a colorless, odorless and tasteless gas, is
highly combustible, burning with a very hot but slightly
luminous flame, and when mixed with air or free oxygen,
explodes with violence.
NITROGEN.
N2.
This gas is seldom used, but when required may be
readily prepared by heating equal parts of concentrated
aqueous solutions of ammonium chloride and potassium or
sodium nitrite.
N H4 CI + KN03 = N3 + KC1 + 2H20.
The operation is conducted in a spacious flask, the
evolved gas mixed with steam, ammonium chloride, and pos-
sibly some oxides of nitrogen, is cooled washed with water
and dried over sulphuric acid. Nitrogen prepared in this
way contains no argon.
Nitrogen is a colorless, odorless and tasteless gas, and
is a non-supporter of combustion.
CHLORINE AND CHLORINE WATER.
Cl2.
Chlorine is prepared by mixing 18 parts of common
salt in lumps with 15 parts of finely pulverized good man-
INORGANIC PREPARATIONS. II
ganese dioxide, free from calcium carbonate ; put the mix-
ture in a flask, pour a completely cooled mixture of 45 parts
of concentrated sulphuric acid and 21 parts of water upon
it, and shake the flask : a uniform and continuous evolution
of chlorine gas will soon begin, which, when slackening
may be easily increased again by the application of a gentle
heat. This method of WlGGERS is excellent, and can be
highly recommended. Conduct the chlorine gas evolved
first through a flask containing a little water, then into a
bottle filled with cold water, and continue the process until
the fluid is saturated. Where it is desired to obtain
chlorine water quite free from bromine, the washing flask
is changed after about one-half of the chlorine has been
expelled, and the gas which now passes over is conducted
into a fresh bottle filled with water. If the chlorine water
is to be quite free from hydrochloric acid, the gas must be
passed through a U tube containing manganese dioxide.
The chlorine water must be protected from the action of
light ; since, if this precaution is neglected, it speedily suf-
fers complete decomposition, being converted into dilute
hydrochloric acid, with evolution of oxygen (resulting from
the decomposition of water). Smaller quantities, intended
for use in the laboratory, are best kept in a stoppered
bottle protected by a case of pasteboard. Chlorine water
which has lost its strong peculiar odor is unfit for use.
CHLORINE FROM CHLORIDE OF LIME IN KIPP'S APPA-
RATUS.
Dry chloride of lime is intimately mixed with plaster
and moistened to such a degree that it can only with diffi-
culty be rolled into balls between the fingers. It is made
12 LABORATORY MANUAL OF
homogeneous by powdering in an iron mortar and beaten
into an iron frame 10-12 m.m. high by means of an iron
mallet. It is then covered with a piece of oilcloth and
submitted to great pressure. The plate of chloride of lime
is then cut into cubes while still in the frame and dried as
quickly as possible at 200 C. The cubes are then preserved
in well-closed vessels. It is used in a Kipp's apparatus
with hydrochloric acid (sp. gr. 1.124) diluted with an
equal volume of water. The acid must be free from sul-
phuric acid.*
When chlorine is generated from bleaching powder and
hydrochloric acid in a Kipp's apparatus, it is advisable, af-
ter using the apparatus, to blow in a little air, otherwise a
slow but continuous action takes place, owing to the ab-
sorption of the chlorine by the acid.f
APPARATUS FOR A CONSTANT SUPPLY OF CHLORINE.
I. Manganese dioxide is used in fragments the size of
peas, and is placed in a two-necked bottle, at the bottom
of which there is a layer of broken glass or pumice. This
stands in a water bath. Hydrochloric acid is supplied
from a reservoir at a higher level by a tube reaching to
the bottom of the layer of glass, a T-piece and stopcocks
allowing the same tube to serve for the removal of the
manganese solution. The corks should be soaked in par-
affin. Suitable drying apparatus can be attached and will
not require replenishing for a long time. The chlorine
begins to come off when the temperature of the bath
reaches 50° C, and by means of a stopcock on the outlet its
* C. Winkler, Ber. 20, 184.
f C. Winkler, Ber. 22, 1076.
INORGANIC PREPARATIONS. I 3
rate is completely under control. The evolution can
speedily be arrested by closing the stopcock at the outlet
of the drying apparatus and emptying the water bath.
The apparatus is then left full of chlorine, and is ready
at any moment to give supply of the gas completely free
from oxygen.*
II. From sodium chloride, pyrolusite, and sulphuric
acid. — It is usually supposed that in this reaction the whole
of the chlorine is evolved in the free state; detailed experi-
ments have, however, shown that this is not the case, but
that the reaction which takes place is as follows :
4NaCl + Mn02 + 3H2S04 = 2NaHS04 f- Na2S04 4- MnCl2+
2H20 + Cl2.
The necessary proportions are, therefore, 5 parts of
pyrolusite, 1 1 parts salt, and 14 parts of sulphuric acid
diluted with an equal volume of water.
III. From pyrolusite, hydrochloric and sulphuric acids.
— The instructions usually given for the preparation of
chlorine by this method are to take 1 part of pyrolusite, 2
of hydrochloric acid of sp. gr. 1.14, and 1 part of sulphuric
acid mixed with an equal bulk of water, the reaction being
supposed to take place according to the equation:
Mn02 + 2HC1 + H2S04 = MnS04 + 2H20 + Cl2.
As in the foregoing case this equation is quite incorrect,
only 65 per cent, of the chlorine being obtained in the free
state.
* A. Vosmaer, Zeit. Anal. Chem., 27, 638.
14 LABORATORY MANUAL OF
CHLORINE FOR LABORATORY PURPOSES.
When hydrochloric acid of sp. gr. i.i, heated to about
8o° C, is allowed to come slowly in contact with pieces of
potassium chlorate which have been previously fused, a
steady evolution of gas takes place. Under these condi-
tions, about 82 to 85 per cent, of the gas is chlorine, the re-
mainder being chlorine dioxide. Another 10 per cent, of
the dioxide may be decomposed by passing the evolved
gas through a saturated hydrochloric acid solution of man-
ganous chloride at 900 C. If the gas is wanted absolutely
pure, the gas, after passing through the manganous chlor-
ide, may be passed through a combustion tube filled with
asbestos and heated to redness. Care must be taken to
have the acid hot, and not to allow the action to become
rapid, or the proportion of chlorine dioxide may become
much increased and explosion occur. 1 gram of potas-
sium chlorate yields about half a litre of chlorine.
If a Kipp or some similar constant gas-generating ap-
paratus is employed, and the acid heated by a steam
jacket or by standing the generator in hot water, this
method forms a convenient constant chlorine apparatus for
laboratory use.*
Chlorine is a heavy greenish, yellowish gas, having a
strong and suffocating odor, and if inhaled in sufficient
quantities is capable of producing suffocation. Free
chlorine gas is readily detected by its color and odor.
* F. A. Gooch and D. A. Kreider, Zeit. Anorg. Chem. , 7, 17.
INORGANIC PREPARATIONS.
HYDROCHLORIC ACID, OR
HYDROGEN CHLORIDE.
HC1.
Pour a cooled mixture of seven parts of concen-
trated sulphuric acid and two parts of water over
four parts of sodium chloride in a retort; expose the re-
tort, with slightly raised neck, to the heat of a sand-bath
until the evolution of gas ceases; conduct the evolved
gas, by means of a bent tube, into a flask containing six
parts of water, and take care to keep this vessel constantly
cool. To prevent the gas from receding the tube ought to
dip but about one line into the water of the flask. When
the operation is terminated, try the specific gravity of the
acid produced, and dilute with water until it marks from
1. 1 1 to 1. 12. If you wish to ensure the absolute purity of
the acid, and its perfect freedom from every trace of arsenic
and chlorine, you must take care to free the sulphuric acid
intended to be used in the process from arsenic and the
oxygen compounds of nitrogen, according to the directions
(see sulphuric acid, page 22.) A pure acid may also be
prepared cheaply from the crude hydrochloric acid of com-
merce by diluting the latter to a specific gravity of 1.12 and
distilling the fluid with addition of some chloride of sodium.
Or you may put the acid into the retort in the concentrated
form, placing 60 parts of water into the receiver for every
100 parts of concentrated acid, and not luting the receiver
to the retort. If the crude acid contains chlorine this
should be removed first by cautious addition of solution of
sulphur dioxide, before proceeding to the distillation; if,
1 6 LABORATORY MANUAL OF
on the other hand, it contains sulphur dioxide, this is re-
moved in the same way by cautious addition of some
chlorine water. Hydrochloric acid not unfrequently con-
tains arsenious chloride, owing to the presence of arsenic
in the sulphuric acid employed. To free it from this im-
purity, the acid is mixed with twice its volume of water,
hydrogen sulphide is conducted into it, the mixture allowed
to stand at rest for some time, the clear fluid then decanted
from the sulphur and arsenious sulphide, and heated, to ex-
pel the hydrogen sulphide.
Hydrochloric acid must be perfectly colorless and
leave no residue upon evaporation. If it turns yellow
on evaporation, ferric chloride is present. It must not im-
part a blue tint to a solution of potassium iodide mixed
with starch paste (chlorine or ferric chloride), nor discolor
a fluid made faintly blue with iodized starch (sulphur
dioxide). Barium chloride ought not to produce a pre-
cipitate in the highly diluted acid (sulphuric acid). Hy-
drogen sulphide must leave the diluted acid unaltered (ar-
senic). After neutralization with ammonia, ammonium
sulphide must produce no change in it (iron, thallium).
It can also be prepared by distilling a mixture of cone.
sulphuric and hydrochloric acids; this latter method is bet-
ter where gaseous hydrochloric acid is needed.
METHODS FOR OBTAINING CONSTANT STREAMS OF HY-
DROGEN CHLORIDE, AMMONIA AND NITROGEN.
Hydrogen chloride can be generated in a Kipp's ap-
paratus by the action of ordinary sulphuric acid on carnal-
lite ; ammonia gas by allowing a solution of ammonia
to react with solid potassium hydroxide. When the ma-
INORGANIC PREPARATIONS.
17
terials are exhausted, the solution of potash which is
formed may be used for ordinary laboratory purposes after
it has been boiled to expel ammonia.
To prepare nitrogen in Kipp's apparatus, it is best to
employ cubes containing chloride of lime made according
to Winkler's method (page 11); these are treated with
a mixture of equal volumes of ammonia and water.
The resulting gas contains suspended ammonium chloride
and other impurities, which may be removed by passing
it through water, potash and sulphuric acid.*
Fig. 4.
NITRIC ACID, or HYDROGEN NITRATE.
HNO3 or N02OH.
Prepared by slowly distilling a mixture of 5 parts of
sodium nitrate and 3 parts of cone, sulphuric acid, in an
apparatus as shown in Fig. 4 ; the product is usually not
By G. Neumann, (J. pr. Chem. [2] 37, 342-345).
I 8 LABORATORY MANUAL OF
sufficiently concentrated, and must be redistilled with five
times its volume of cone, sulphuric acid in an apparatus
similiar to the above. If the product is colored yellow or red
by dissolved oxides of nitrogen, it may be rendered color-
less by blowinga current of dry air through the acid for some
minutes. Concentrated nitric acid 1.53 spcific gravity
has a strong affinity for water and must be kept closely stop-
pered.
The sudden frothing which frequently takes place when
nitric acid is prepared from sodium nitrate and sulphuric
acid is explained on the assumption that the first portions
pass over at 840 C, and that the heating mustbe commenced
cautiously, and the temperature only allowed to rise after
the first reaction abates. After the temperature has risen
above 1090 C, no acid passes over until the temperature
1 1 70 C. is reached, when the last portions pass over. The
latter acid has a sp. gr. 1.42, and corresponds with the
hydrate, HN03 -f- 2H30,' which distills at 120 to 12 1° C.
without decomposition.*
Another method of preparation is to heat crude nitric
acid of commerce, as free as possible from chlorine, and of
a specific gravity of at least 1.3 1 in a glass retort to
boiling, with addition of some potassium nitrate ; let the
distillate run into a receiver kept cool, and try from time
to time whether after dilution it still continues to precipi-
tate or cloud solution of silver nitrate. As soon as this
ceases to be the case, change the receiver, and distill until
a trifling quantity only remains in the retort. Dilute the
distillate with water until the specific gravity is 1.2.
* By C. W. Volney, J. Amer. Chem. Soc. 13, 246-251.
INORGANIC PREPARATIONS. 19
Another method is to dilute crude nitric acid of com-
merce of about 1.38 specific gravity with two-fifths of its
weight of water, and add solution of silver nitrate as long
as a precipitate of silver chloride continues to form ; then
add a further slight excess of solution of silver nitrate, let
the precipitate subside, decant the perfectly clear super-
natant acid into a retort or an alembic with ground head ;
add some potassium nitrate free from chlorine, and distill
until only a small quantity remains, taking care to attend
to the proper cooling of the fumes distilling over. Dilute
the distillate, if necessary, with water until it has a specific
gravity of 1.2.
Pure nitric acid must be colorless and leave no
residue upon evaporation on platinum foil. Solution of
silver nitrate or of barium nitrate must not cause the
slightest turbidity in it. Dilute the acid with water before
adding these reagents, as otherwise nitrates will pre-
cipitate. Silver should be tested for by hydrochloric acid.
NITROUS OXIDE.
N30.
Five parts of stannous chloride, 10 parts of hydrochloric
acid sp. gr. 1.2 1, and 0.9 part of nitric acid sp. gr. 1.38,
are heated to boiling, when the evolution of nitrous oxide
commences, and continues to be evolved quite regularly
and in a pure state. The above proportions of ingredients
should be adhered to, as otherwise the gas is evolved ir-
regularly, and even with violent explosions.*
G. Campori, Ann. Chine. Pharm., 8, 253.
20 LABORATORY MANUAL OF
It can also be prepared from a mixture of ammonium
sulphateand sodium nitrate, kept at 1020 C. for 2 to 3 hours,
undergoing in great partdecomposition into sodium sulphate
and ammonium nitrate. If, however, it is rapidly raised
to a higher temperature, nitrous oxide begins to be evolved
atiio° C.,and comes off with some rapidity at 115 to 1200
C. During the heating up a little ammonia is evolved, and
the longer the mixture is kept at about 104 to 1 io° C. the
more ammonia is lost. If, then, the two salts have been mixed
in molecular proportions, the deficiency in the ammonia
leads to the evolution of some of the higher oxides of nitro-
gen towards the end of the reaction. This may be remedied
by increasing the proportion of ammonium sulphate, the
mixture, with an additional 5 per cent, of that salt, affording
a larger yield of nitrous oxide than would be obtained from
the equivalent quantity of ammonium nitrate. The gas is
evolved with regularity, whereas ammonium nitrate, raised
to 1 1 5Q C, decomposes with a rapidity, accelerating towards
explosive violence.*
NITRIC OXIDE.
NO.
A Woulff's bottle, fitted with a funnel and delivery
tube, is filled loosely with strips of copper, and then one-
third with a cold saturated solution of sodium nitrate.
Strong sulphuric acid is added more or less rapidly, ac-
cording to the amount of gas required. The evolution of
gas is very regular, and may be kept up for hours.f
* By W. Smith, J0 Soc. Chem. Ind., 11,867; 12, 10.
f By H. Kaemmerer, Ber. 18, 3064-3066.
INORGANIC PREPARATIONS. 21
Nitric oxide may also be prepared from a mixture of
solutions of potassium ferrocyanide and potassium nitrite
added gradually from a stoppered funnel to a flask contain-
ing acetic acid ; the contents of the flask must be vigor-
ously shaken during the operation.*
Another method is to add a strong solution of
sodium nitrite to a solution of ferrous chloride or sulphate
in hydrochloric acid. If the sodium nitrite contains car-
bonate, it should be removed by precipitation with calcium
chloride. f
In order to obtain this gas in a very pure condition, the
reaction which takes place in a Lunge's nitrometer is
employed; namely, treating mercury with a mixture of
sulphuric acid and nitric acid. The purity of the gas is
placed beyond question by the results obtained on leading it
over glowing copper; the increase in weight of the metal,
giving the weight of oxygen, w"hilst the gas evolved, which
is collected and measured, gives the weight of nitrogen.
In the reaction between copper and nitric oxide, which is
attended by the liberation of much heat, the metal is
quantitatively converted into cuprous oxide.f
NITROGEN TETROXIDE.
N204.
200 grams arsenious acid in pieces the size of a pea
are placed in a tubulated retort with bent neck, 200 grams
nitric acid 1.38 sp.gr. poured over it, and very moderately
* By C. M. Van Deventer, Ber. 26, 589-593.
f By J. Thiele, Annalen, 253, 146.
X By F. Enrich, Monatsch., 13, 73-77.
22 LABORATORY MANUAL OF
warmed. The evolved gas passes into an empty wash-
bottle, is then dried by a tube filled with calcium nitrate
and is finally conducted into a wide combustion-tube which
is surrounded by a freezing mixture of ice and common salt.
A dark-green liquid condenses in this tube. Dry oxygen
gas is conducted into it until the liquid has changed to
a pure yellow, then the tube is sealed.
The arsenic trioxide reduces the nitric acid passing
into arsenic acid. In drying the gases calcium chloride
must not be used, as they would be contaminated with
chlorine, nor sulphuric acid, as it absorbs the gases.
The condensed mixture of nitrogen trioxide and tetroxide
is transformed by oxygen into pure tetroxide.'
The liquid should show a sp. gr. of 1.45 and boil at
25 to 260 C. On cooling rapidly it should congeal to a
colorless crystal mass, which melts at about 120 C.
SULPHURIC ACID or HYDROGEN SULPHATE.
H3S04 or S03(OH)2.
a. Concentrated pure sulphuric acid.
b, Concentrated sulphuric acid of commerce.
c Common dilute sulphuric acid.
The following method may be recommended for
preparing chemically pure sulphuric acid :
a. Mix 1,000 grams of ordinary concentrated sulphuric
acid and 3 grams of ammonium sulphate in a porcelain
dish, and heat till copious fumes of S03 begin to escape,
in order to destroy the oxides of nitrogen which are
present. After cooling, add 4 or 5 grams of powdered
manganese dioxide, and heat to boiling while stirring, in
INORGANIC PREPARATIONS. 23
order to convert any arsenious acid into arsenic acid.
When cool pour off the clear fluid by means of a long
funnel tube into a retort coated with clay. The retort
should not be more than half full, and is to be heated
directly over charcoal. To prevent bumping, rest the
retort on an inverted crucible cover, so that the sides may
be more heated than the bottom. The neck of the retort
must reach so far into the receiver that the acid, distilling
over, drops directly into the body. To cool the receiver
by means of water is unnecessary and even dangerous.
To prevent the receiver from coming into actual contact
with the hot neck of the retort, some asbestos in large
fibres is placed between them. When about 10 or 15
grams has been drawn over, change the receiver and slowly
distil off three-fourths of the contents of the retort. This
method depends upon the fact discovered by Bussy
and Buignet, that on distilling sulphuric acid, which
contains arsenic in the form of arsenic acid, an arsenic-free
distillate is obtained.
b. Pour into 4 parts of water 1 part of concentrated
sulphuric acid, and conduct into the mixture for some time
a slow stream of hydrogen sulphide, keeping the fluid
heated to yo° C. Let the mixture stand at rest for several
days, then decant the clear supernatant fluid from the
precipitate, which consists of sulphur, lead sulphide, per-
haps also arsenic sulphide, and heat the decanted fluid in a
tubulated retort with upturned neck and open tubulature
until sulphuric acid fumes escape with the aqueous
vapor. The acid so purified is fit for many purposes
of chemical analysis ; if it is desired, however, to free
it also from non-volatile substances, it may be distilled
24 LABORATORY MANUAL OF
from a coated retort as in a. As soon as the drops in the
neck of the retort become oily, the receiver is changed,
and the concentrated acid which then passes over is kept
in a separate vessel.
c. Common dilute sulphuric acid. — Add to 5 parts of
water in a thin glass or porcelain dish gradually, with
constant stirring, 1 part of concentrated sulphuric acid.
The lead sulphate which seperates is allowed to subside,
and the clear fluid finally decanted.
Pure sulphuric acid must be colorless; when a colorless
solution of ferrous sulphate is poured upon it in a test
tube, no brown tint must mark the plane of contact of
the two fluids (nitric acid, nitrous acid); when diluted
with twenty parts of water it must not impart a blue tint
to a solution of potassium iodide mixed with starch paste
(nitrous acid). Mixed with pure zinc and water, it yields
hydrogen gas, which, on being passed through a red-
hot tube, should not deposit the slightest trace of
arsenic. It should leave no residue upon evaporation
on platinum, and must remain perfectly clear upon dilu-
tion with four or five parts of alcohol (lead, iron, calcium).
The presence of small quantities of lead is detected most
easily by adding some hydrochloric acid to the sulphuric
acid in a test tube. If the plane of contact is marked
by turbidity (lead chloride), lead is present. Sulphurous
acid is discovered by the odor after shaking the acid in a
half-filled bottle.
INORGANIC PREPARATIONS.
25
HYDROGEN SULPHIDE. HYDROSULPHURIC
ACID. SULPHURETTED HYDROGEN.
H3S.
Hydrogen sulphide is usually evolved from iron
sulphide, which is broken into small lumps and then
treated with dilute sulphuric or hydrochloric acid. Fused
iron sulphide may be purchased cheaply, or may be made
by heating iron turnings or I to I ^ inch iron nails, in a
covered Hessian crucible to a white heat, and then adding
Fig. 6.
small lumps of roll-sulphur until the entire contents of the
crucible are in fusion. As soon as this is the case, pour
the fused mass upon sand, or into an old Hessian crucible.
Or make a hole in the bottom of the crucible, when the
iron sulphide will run through as fast as it forms, and may
26 LABORATORY MANUAL OF
be received in a shovel placed in the ash-pit. Or intro-
duce an intimate mixture of thirty parts of iron filings and
twenty-one parts of flowers of sulphur in small portions
into a red-hot crucible, awaiting always the incandescence
of the portion last introduced before proceeding to the
addition of a fresh one. When you have thus put the
mixture into the crucible, cover the latter closely, and
expose it to a more intense heat, sufficient to make the
iron sulphide fuse more or less, then allow the crucible to
cool and break the sulphide in small pieces.
The iron sulphide is then placed in a Kipp's apparatus,
(Fig. 6,) and the gas is generated by the action of dilute
sulphuric or hydrochloric acids.
HYDROGEN SULPHIDE FREE FROM ARSENIC.
Calcium sulphide (prepared by igniting a mixture of
plaster of Paris and coal) yields the pure gas when treated
with dilute hydrochloric acid. To evolve the gas in a
regular stream, a mixture of calcium sulphide, with one-
fourth of its weight of plaster of Paris and enough water to
make a cream, is poured into shallow paper trays. As
soon as it has set, the cake is cut up into blocks, which
are dried at a gentle heat. They may be used in Kipp's
apparatus.*
Another method is to use barium sulphate (powdered
barytes) mixed with 25 per cent, of ground coal and 20
per cent, of common salt. The dampened mixture is
rammed into a clay crucible, which, after drying and
closing with a luted cover, is heated for several hours
* R. Fresenius, Zeit. Anal. Chem. 26, 339.
INORGANIC PREPARATIONS. 2J
at an incipient white heat. The product is in hard com-
pact masses which dissolve completely in dilute hydro-
chloric acid with a steady evolution of hydrogen sul-
phide.*
HYDROGEN SULPHIDE FREED FROM HYDROGEN
ARSENIDE.
This method is based on the fact that hydrogen arsen-
ide reacts violently with iodine at ordinary temperature,
arsenious iodide and hydrogen iodide being formed.
A narrow tube, 30 to 40 cm. long, is loosely filled with
coarsely powdered, air-dried iodine interspersed with glass
wool; 2 or 3 grams of iodine will remove every trace of ar-
senic from hydrogen sulphide prepared from the ordinary
impure materials, by passing over it for several days. In
purifying hydrogen, the latter is subsequently passed over
glass wool wetted with potassium iodide solution and then
through aqueous potash. f
Free hydrogen sulphide in quantity is readily detected
by its odor, and its blackening effect upon paper moist-
ened with lead acetate solution.
SULPHUR DIOXIDE.
so2.
Prepared by gently heating in a flask scrap copper with
concentrated, sulphuric acid
Cu 4- 2H2S04 = SOg + 2H20 + CuS04.
It can be absorbed in water and used as a solution of sul-
phurous acid or absorbed in caustic alkalies forming
* C. Winkler, Zeit. Anal. Chem. 27, 26.
f O. Jacobsen, Ber. 20, 1999.
28 LABORATORY MANUAL OF
bisulphites which may be again used to generate sulphur
dioxide by the action of cone, sulphuric acid.
Prepared in this way, however, it is liable to contain
sulphuric acid which is not readily removed. Sulphur
dioxide is now obtainable in liquified condition and as
such is used for disinfecting and freezing purposes.
Sulphurous anhydride (S03) can be generated in
Kipp's apparatus by the action of ordinary concentrated
sulphuric acid on cubes prepared by Winkler's method
from a mixture of 3 parts of calcium sulphite and 1 part of
plaster. Economy in the use of cubes is effected if only
the number required for the generation of the amount of
gas needed are wetted with the acid at the commencement
of the operation.*
Sulphur Dioxide is recognized —
1st. By its odor which is marked and well-known, re-
sembling that of burning matches.
2nd. Suspend in the gas a strip of paper which has
been dipped into a solution of starch paste and potassium
iodate. Iodine is liberated and the paper becomes blue.
2KI03 + 5S02 + 4HgO = 2HKS04 + 3H3S04 -f I2.
CARBON MONOXIDE.
CO.
Prepared by gently heating commercial oxalic acid in
a capacious flask with cone, sulphuric acid. The acid
exerts a dehydrating action and a mixture of carbon mon-
oxide and carbon dioxide is evolved. The mixed gases are
G. Neumann, Ber. 20, 1584.
INORGANIC PREPARATIONS. 29
passed through potassium hydrate solution which absorbs
the carbon dioxide and sulphuric acid ; any water which
may be present being removed by passing the gases
through concentrated sulphuric acid.
Another and better method is as follows :
A mixture of finely powdered potassium ferrocyanide
with eight or ten times its weight of cone, sulphuric acid is
heated in a capacious flask ; the following reaction results:
K4Fe(CN)6 + 6H3S04 + 6H20 =
6CO + 2K2S04 4- 3(NH4)2S04 + FeS04.
If the heat is carefully regulated the evolution of gas is
gentle and regular. The product, however, is liable to
contain carbon dioxide and cyanogen compounds, hence it
is better to wash with potassium hydrate solution. Carbon
monoxide is recognized when in sufficient quantities by the
bluish flame with which it burns.
CARBON DIOXIDE.
C02.
Prepared by treating coarsely broken marble with dilute
acids in Kipp's Apparatus, washing with water and drying
over cone, sulphuric acid. It is used to remove chlorine in
various operations where heat is undesireable. The gas
may now be obtained in the liquid form, in steel cylin-
ders and is used as a freezing agent.
The free gas is detected by conducting it through a
solution of calcium hydroxide, Ca(OH)2 with which it
forms a white precipitate (calcium carbonate).
The free gas in water may be detected by adding the
same solution as above.
30 LABORATORY MANUAL OF
SIMPLE AND RAPID PREPARATION OF PURE GASES.
Instead of using an acid for the evolution of carbonic
anhydride, sulphurous anhydride, and similar gases, it is
convenient to use sodium hydrogen sulphate. A mixture
of equivalent quantities of the respective salts in powder
gives, when wetted with water, a regular stream of the re-
quired gas, which will be free from the impurities usually
derived from the use of an acid.*
AMMONIA,
NH,
AMMONIUM HYDRATE.
NH4OH.
Prepared by gently heating crude ammonium chloride
with dry slaked lime
2NH4CI + Ca(OH)2 = 2NH3 + CaCI2 4- 2H30
2NH3 + 2H30 = 2NH4OH.
If gaseous ammonia is needed it must be caught by
downward displacement of air, otherwise the gas is passed
into water until saturated.
To make ammonia for laboratory use the strongest
ammonia water is dropped on porous calcium chloride,
great heat is evolved during this operation but the gas
which passes over is almost pure.
* By H. Borntraeger, Zeit. Anal. Chem., 29, 140.
INORGANIC PREPARATIONS. 3 I
POTASSIUM HYDROXIDE, or POTASSA,
KOH,
and SODIUM HYDROXIDE, or SODA,
NaOH.
The preparation of perfectly pure potassa or soda is a
difficult operation. It is advisable, therefore, to provide
besides perfectly pure caustic alkali, some which is not
quite pure, and some which, being free from certain im-
purities, may in many cases be substituted for the pure sub-
stance.
a. Common solution of Soda. — Put into a clean cast-iron
pan provided with a lid, 3 parts of crystallized sodium car-
bonate of commerce and 15 parts of water, heat to boiling,
and add, in small portions at a time, thick milk of lime pre-
pared by pouring 3 parts of warm water over 1 part of
fresh-burned quick-lime, and letting the mixture stand in
a covered vessel until the lime is reduced to a uniform
pulpy mass. Keep the liquid in the pan boiling while
adding the milk of lime, for a quarter of an hour
longer ; then filter off a small portion, and test whether the
filtrate still causes effervescence in hydrochloric acid. If
this is the case, the boiling must be continued, and if
necessary some more milk of lime must be added to the
fluid. When the solution is perfectly free from carbonic
acid, cover the pan, allow the fluid to cool a little, and
then draw off the nearly clear solution from the residuary
sediment, by means of a siphon filled with water, and
32 LABORATORY MANUAL OF
transfer it to a glass flask. Boil the residue a second and
third time with water, and draw off the fluid in the same
way. Cover the flask close with a glass plate, and allow
the lime suspended in the fluid to subside completely.
Scour the iron pan clear, pour the clear solution back into
it, and evaporate it to 6 or 7 parts. The solution so pre-
pared contains from 9 to 10 per cent, of soda, and has
a specific gravity of from 1. 13 to 1. 15. If it is wished to
filter a solution of soda which is not quite clear, a cov-
ered funnel should be used, which has been charged first
with lumps of white marble and then with powder of the
same, the fine dust being rinsed out with water before the
filter is used (Graeger). Solution of soda must be clear,
colorless, and as free as possible from carbonic acid ; am-
monium sulphide must not impart a black color to it.
Traces of silicic acid, alumina, and phosphoric acid are usu-
ally found in a solution of soda prepared in this manner,
on which account it is unfit for use in accurate experi-
ments. Solution of soda is kept best in bottles closed with
ground glass caps. In default of capped bottles, common
ones with well-ground stoppers may be used, in which case
the neck must be wiped perfectly dry and clean inside and
the stopper coated with paraffine ; since, if this precaution
is neglected, it will be found impossible after a time to
remove the stopper, particularly if the bottle is only rarely
opened.
Absolutely pure soda is best prepared by dissolving
sodium in pure water in a silver dish (adding but very
small pieces at a time) and evaporating until a drop of the
liquid solidifies on cooling.
The strength of the caustic soda solution is ascertained
approximately by specific gravity.
INORGANIC PREPARATIONS. 33
% NaOH. Sp. Gr. % NaOH. Sp. Gr.
IO I.-H5 21 1 .236
II.... 1.126 22 I.247
12 1. 137 23 I258
13 1. 148 24 1.269
14 i-i59 25 I279
15 1.1 70 26 1.290
16 1. 181 27 1-300
17 1. 192 28 1 .310
18 1.202 29 1 .32 1
19 .1.213 30 1.332
20 ... 1.225
The exact strength may be determined by titrating
say 20 c. c. of the solution with normal acid, using phen-
olphthalein as indicator, if any carbonic acid is present, a
small quantity of barium chloride solution should be
added before titrating. The calculation is very simple
since 1 c. c. N/HC1 or N/'2H2S04 = 0.040 gram. NaOH or
0.0561 KOH.
b. Potassa purified with alcohol. — Dissolve some caus-
tic potassa of commerce in alcohol, in a stoppered bottle,
by digestion and shaking ; let the fluid stand, decant it, or
filter it if necessary, and evaporate the clear fluid in a sil-
ver dish over the gas or spirit lamp until no more vapors
escape, adding from time to time, during the evaporation,
some water to prevent blackening of the mass. Place the
silver dish in cold water until it has sufficiently cooled ; re-
move the cake of potassa from the dish, break in coarse
lumps in a hot mortar and keep in a well closed glass bot-
tle. When required for use, dissolve a small lump in
water.
34 LABORATORY MANUAL OF
The potassa so prepared is sufficiently pure for most
purposes ; it contains a minute trace of alumina, but is
usually free from phosphoric, sulphuric, and silicic acids.
The solution must remain clear upon addition of ammonium
sulphide ; hydrochloric acid must only produce a barely
perceptible effervescence in it. The solution acidified with
hydrochloric acid must, upon evaporation to dryness, leave
a residue which dissolves in water to a clear fluid. The
solution acidified with hydrochloric acid, and then mixed
with ammonia in the least possible excess, must not show
any flocks of alumina, at least until it has stood in a warm,
place for several hours. The solution acidified with nitric
acid must not give any precipitate with a nitric acid solu-
tion of ammonium molybdate.
Potassa prepared with baryta. — Dissolve pure crystals
of baryta by heating with water, and add to the solution
pure potassium sulphate until a portion of the filtered fluid,
acidified with hydrochloric acid and diluted, no longer
gives a precipitate on addition of a further quantity of the
sulphate (16 parts of crystals of baryta require 9 parts of
potassium sulphate). Let the turbid fluid clear, decant
and evaporate in a silver dish. The potassa so prepared
is perfectly pure, except that it contains a trifling admix-
ture of potassium sulphate, which is left behind upon dis-
solving in a little water. It is but rarely required, its use
being in fact exclusively confined to the detection of
minute traces of alumina
INORGANIC PREPARATIONS. 35
BARIUM HYDROXIDE, OR BARYTA.
Ba(OH)2.
There are many ways of preparing baryta ; but
as witherite (barium carbonate) is now cheaply procurable,
the following method is preferable: Mix intimately to-,
gether ioo parts of finely pulverized witherite, 10 parts
of charcoal in powder, and 5 parts of rosin, put the mix-
ture in an earthenware crucible, lute on the lid with clay,
and expose the crucible so prepared to the heat of a brick-
kiln. Break and triturate the baked mass, boil repeatedly
with water in an iron pot, filter into bottles, stopper, and
let them stand in the cold, when large quantities of crystals
of barium hydroxide Ba(OH)s -f 8H30 will make their
appearance. Let the crystals drain in covered funnels,
dry rapidly between sheets of blotting paper, and keep
them in well closed bottles. For use, dissolve 1 part of the
crystals in 20 parts of water, with the aid of heat, and filter
the solution. The baryta water so prepared is purer than
the mother liquor running off from the crystals. The res-
idue, which is insoluble in water and consists of undecom-
posed witherite and charcoal, may be turned to account in
the preparation of barium chloride.
Baryta water must, after precipitation of the barium
by pure sulphuric acid, give a filtrate remaining clear when
mixed with alcohol, and leaving no fixed residue upon
evaporation in a platinum crucible.
Barium hydroxide being a strong base, precipi-
tates the metallic hydroxides insoluble in water from the
solutions of their salts.
$6 LABORATORY MANUAL OF
CALCIUM HYDROXIDE, or LIME.
Ca(OH)2.
Calcium hydroxide is obtained by slacking lumps of
pure calcined lime in a porcelain dish, with half their
weight of water. The heat which accompanies the com-
bination of the lime and the water is sufficient to evapor-
ate the excess of water. Slacked lime must be kept in a
well-stoppered bottle.
To prepare lime water, digest slacked lime for some
time with cold distilled water, shaking the mixture occa-
sionally ; let the undissolved portion of lime subside, de-
cant, and keep the clear fluid in a well-stoppered bottle.
If it is wished to have the lime water quite free from all
traces of alkalies, baryta and strontia, which are almost
invariably present in slacked lime prepared from calcined
limestone, the liquids of the first two or three decantations
must be removed, and the .fluid decanted afterwards alone
made use of.
Lime water must impart a strongly-marked brown
tint to turmeric paper, and give a not too inconsider-
able precipitate with sodium carbonate. It speedily loses
these properties upon exposure to the air.
LEAD DIOXIDE.
Pb02.
a. In the dry way. 53 grams lead oxide are thor-
oughly mixed in a mortar with 50 grams calcium carbonate,
and a wide and not too deep clay crucible is filled loosely
INORGANIC PREPARATIONS.
37
with the mixture and heated in Roessler's gas furnace (fig.
7) for half an hour to fusion, regulating the draft so that
there shall be an excess of air in the fusion chamber.
After having cooled the slightly baked frit, it is powdered
Fig. 7.
in a mortar and once more heated for half an hour at a red
heat. A powdered sample of the product is covered with
diluted HN03; if carbonic acid is evolved, the powdered
mass is to be heated a short while longer to white heat.*
* The oxydation goes on rapidly, if the mixture is heated in an infusi-
ble clay dish (iron is impracticable, as it corrodes rapidly in Roessler's gas
furnace at a high temperature). As soon as the mass begins to glow, stir
vigorously with an iron spatula. During the process the small opening in
the cover of the furnace is not closed.
38 LABORATORY MANUAL OF
The finely powdered, flesh-colored calcium plumbate is
poured gradually into 200 c. c. diluted HN03 ; after set-
tling, it is decanted and ground in a mortar with fresh
HNO3 (100 c. a). Finally it is once more boiled up with
diluted HNO3, filtered, rinsed with hot water and dried on
the waterbath. For most purposes it is more convenient
to merely decant the peroxide with hot water and preserve
it as paste. The weight of the lead peroxide obtained
about equals that of the lead oxide taken.*
b. In the wet way. A solution of 190 grams lead
acetate in 500 c. c. water is mixed with 500 c. c. of 20%
soda lye and the cooled milky, alkaline solution treated by
shaking with chlorine until no further precipitation takes
place. It is then washed with water by decantation and
purified, as above, with nitric acid.
By the aid of atmospheric oxygen and lead oxide, the
carbonic acid of the calcium carbonate is expelled with
formation of calcium plumbate corresponding with the
orthosilicates : 2CaC03 + PbO + O = Ca2Pb04 + 2C02.
The plumbate varying only very little in color from the
original mixture, is easily decomposed with HNO3 :
Ca2Pb04 + 4HN03 = 2Ca(N03)2 + Pb02 + 2H20.
In aqueous solution lead peroxide is formed through
the action of chlorine on sodium lead oxide: Pb(ONa)2 -f
2C1 = Pb02 + 2NaCl.
The dark-brown leade peroxide, after being boiled with
diluted HNO3, must not impart a violet color to the super-
natant solution ; this color should appear immediately
upon adding a drop of diluted manganese sulphate solu-
* Kassner, Chem. Ind. 13, 1890, 104-120.
INORGANIC PREPARATIONS. 39
tion.* Suspended in diluted HN03, it should dissolve
readily and entirely upon addition of sodium nitrite. To
determine the quantity of lead peroxide, an average sam-
ple of the paste or the finely powdered preparation is
weighed, placed into a flask with ground glass stopper,
covered with diluted HNO3 and gradually add a small ex-
cess of normal sodium nitrite, aiding the reaction by fre-
quent and vigorous shaking of the closed bottle. After all
the peroxide has passed into solution, it is diluted with a
large quantity of water and the excess of nitrite titrated
back with potassium permanganate.
Lead dioxide, when boiled with thrice its bulk
of pure nitric acid for several minutes and allowed to
settle, must not communicate the faintest red color to the
acid (absence of manganese).
LEAD CARBONATE.
PbC03.
Lead oxide is readily converted into soluble hydroxide
on treatment with a moderately concentrated solution of
magnesium acetate. The solution thus obtained has an
alkaline reaction, and yields lead carbonate when treated
with carbonic anhydride. The white precipitate is col-
lected, washed and dried, and the solution of magnesium
acetate concentrated and used for another operation.!
* Manganese protoxide is oxydized in nitric solution by lead peroxide
into permanganic acid, Pb02 + HN02 + HN03 = Pb(N03)2 + H20.
f W. Kubel, Dingl. Polyt. j. 262. 143,
40 LABORATORY MANUAL OF
LEAD TETRACHLORIDE.
Pb.Cl4.
When lead dichloride is suspended in hydrochloric acid
and gaseous chlorine passed into the liquid, a solution of
lead tetrachloride is obtained, from which, on addition of
ammonium chloride, a compound, PbCl2NH4Cl, analogous
to ammonium stanic chloride, separates. If this com-
pound is added to concentrated sulphuric acid, an en-
ergetic reaction ensues, and lead tetrachloride separates as
an oily substance ; it is purified by shaking with fresh
quantities of sulphuric acid. In the pure state, it is a
translucent, yellow, highly refractive liquid which fumes
in contact with moist air, with decomposition into lead
dichloride and chlorine ; it may be kept under cold con-
centrated sulphuric acid, but when heated with it, it de-
composes with explosion into lead dichloride and chlorine.
When, however, lead tetrachloride is heated in a retort
with concentrated sulphuric acid, and a current of chlorine
passes through, a certain quantity of the tetrachloride distils
over below 105 ° C, at about which temperature explosion
occurs. The sp. gr. of lead tetrachloride at o° C. is 3.18,
and it solidifies to a yellowish crystalline mass at 150 C; it
forms a hydrate in the presence of a little water, which, by
the further addition of water, decomposes into lead perox-
ide and hydrogen chloride ; when brought in contact with
a small quantity of cooled hydrochloric acid, a crystalline
derivative, probably PbCl42HCl, is formed.
* By H. Friedrich, Ber. 26, 1434-1436 ; compare Abetr., 1890, 699
also Classen and Zahorski, Zeit. anorg. Chem. 4, 100.
INORGANIC PREPARATIONS. 41
BISMUTH HYDROXIDE.
BiOOH.
Dissolve bismuth, freed from arsenic by fusion with
kepar sulphuris* in dilute nitric acid; dilute the solu-
tion until a slight permanent precipitate is produced ;
filter and evaporate the filtrate to crystallization. Wash
the crystals with water containing nitric acid, triturate
them with water, add ammonia in excess, and let the mix-
ture digest for some time ; then filter, wash and dry the
white precipitate.
The bismuth hydroxide is dissolved in dilute nitric
acid and precipitated with sulphuretted hydrogen. Part
of the precipitated sulphide is treated with ammonia and
filtered, and part treated with ammonium sulphide and
filtered. The nitrates are then mixed with hydrochloric
acid in excess ; the first should give no precipitate and the
second only a white precipitate of sulphur.
AMMONIUM SULPHIDE.
a. Colorless ammonium mono sulphide. (NH4)3S.
a. Transmit hydrogen sulphide through 3 parts of
ammonia solution until no further absorption takes
place; then add 2 parts more of the same ammonia
solution. The action of hydrogen sulphide upon ammonia
gives rise to the formation, first, of (NH4)2S, (2NH4OH)
and H2S = (NH4)3S and 2(H30)], then of NH4SH ; upon
addition of the same quantitv of solution of ammonia as
* Made by fusing potassium carbonate and sulphur. (Watts' Chem.
P- 373 )
42 LABORATORY MANUAL OF
has been saturated, the ammonia decomposes with the am-
monium hydrosulphide and ammonium monosulphide is
formed, thus: NH4SH + NH4OH = (NH4)2S + H20.
The rule, however, is to add only two-thirds of the quan-
tity of solution of ammonia, as it is better the prepara-
tion should contain a little ammonium hydrosulphide than
that free ammonia should be present. To employ am-
monium hydrosulphide instead of the simple monosulphide
is unnecessary, and tends to increase the smell of sulphur-
etted hydrogen in the laboratory, as the preparation al-
lows that gas to escape when in contact with metallic acid
sulphides.
Ammonium sulphide should be kept in well- corked
vials. It is colorless at first, and deposits no sulphur upon
addition of acids. Upon exposure to the air, however, it
acquires a yellow tint, owing to the formation of am-
monium disulphide, which is attended also with formation
of ammonia and water, thus: 2(NH4)3S + O = (NH4)2S2
+ 2NH3 + H20. Continued action of the oxygen of the
air upon the ammonium sulphide tends at first to the for-
mation of still higher sulphides ; but afterwards the fluid
deposits sulphur, and finally all the ammonium sulphide is
decomposed and the solution contains nothing but am-
monia and ammonium thiosulphate. The formation of
thiosulphate proceeds thus: (NH4)2S2 + 03 = (NH4)2S203.
b. Yellow ammonium poly sulphide. (NH4)2SX.
b. The ammonium sulphide which has turned yellow
by moderate exposure to the air may be used for all pur-
poses requiring the employment of yellow ammonium
sulphide. The yellow sulphide may also be expeditiously
prepared by digesting the monosulphide with some sul-
INORGANIC PREPARATIONS. 43
phur. All kinds of yellow ammonium sulphide deposits
sulphur and look turbid and milky on being mixed with
acids.
Ammonium sulphide must strongly emit the odor
peculiar to it; with acids it must evolve abundance of
sulphuretted hydrogen ; the evolution of gas may be
attended by the separation of a pure white precipitate, but
no other precipitate must be formed. Upon evaporation
and exposure to a red heat in a platinum dish it must
leave no residue. It must not, even on heating, precipi-
tate or render turbid solution of magnesium sulphate or
solution of calcium chloride (free ammonia, ammonium
carbonate).
SODIUM SULPHIDE.
Na2S.
POTASSIUM SULPHIDE.
K2S.
Preparation same as for ammonium sulphide, except
that solutions of soda or potrassa are substituted for the
ammonia. Filter, if necessary, and keep the fluid obtained
in well-stoppered bottles. If required to contain some
higher sulphides, digest with powdered sulphur.
AMMONIUM OXALATE.
(NH4)3CA, 2Aq.
Dissolve commercial oxalic acid to saturation in hot
hydrochloric acid of 10 to 12 per cent., cool rapidly
44 LABORATORY MANUAL OF
with constant agitation, wash the crystals (best with
help of a filter pump) with cold water to remove
most of the hydrochloric acid, redissolve in hot water, fil-
ter hot to separate dirt, cool again with stirring, and wash
the crystals with cold water until chlorine is mostly re-
moved.*
Dissolve the pure oxalic acid in 2 parts of distilled
water, with the aid of heat, add solution of ammonia until
the reaction is distinctly alkaline, and put the vessel in a
cold place. Let the crystals drain. The mother liquor
will, upon proper evaporation, give another crop of crys-
tals.
The solution of ammonium oxalate must not be
precipitated nor rendered turbid by hydrogen sulphide, nor
by ammonium sulphide. Ignited on platinum, the salt
must volatilize without leaving a residue.
SODIUM ACETATE.
NaC2H302 3Aq.
Dissolve crystallized sodium carbonate in a little water,
add to the solution acetic acid to slight excess, evaporate
to crystallization, and purify the salt by recrystallization.
Sodium acetate must be colorless and free from empy-
reumatic matter and inorganic acids.
* Stolba.
INORGANIC PREPARATIONS. 45
PURE SODIUM CHLORIDE.
NaCl.
500 grams of common salt are triturated with 1500 c. c.
cold water in a mortar of 3 litres capacity, filtered through
a folded filter into a porcelain dish of about 3 litres and
heated on a gas stove. Then add milk of lime, prepared
from 5 grams caustic lime, and barium chloride solution
in small excess. After settling, it is filtered into a
beaker and the clear fluid precipitated with soda solution
(prepared from 15 grams pure, dry sodium carbonate).
The filtrate is neutralized at a boiling heat with dilute
hydrochloric acid (about 25 c. c.) and as quickly as possible
evaporated over a large burner to y2 litre. The separated
sodium chloride is collected on a funnel fitted with a
platinum cone, sucked dry with the filter pump, washed
with aicohol, and the salt further dried by warming in a
platinum or porcelain dish, stirring constantly with a
platinum spatula or glass rod.
The magnesium and iron contained in the common
salt are precipitated by the calcuim hydrate as hydroxides.
MgCl2 + Ca(OH)2 = Mg(OH)2 + CaCl2.
The sulphuric acid precipitated by the barium chloride.
CaS04 + BaCU = BaS04 4- CaCl2.
The alkaline earths finally separated as carbonates.
CaCl2 + Na2C03 = CaC03 -f 2NaCl.
Sodium chloride forms a snow-white crystalline powder
consisting of small squares. The dried salt warmed
in small dry tubes should not decrepitate ; and at a
46 LABORATORY MANUAL OF
higher temperature it should melt to a perfect liquid. The
watery solution should be examined with ammonium oxa-
late, sodium phosphate, potassium ferrocyanide and barium
chloride for presence of calcium, magnesia, iron and sul-
phuric acid. One drop of the solution with ten drops of
platinum chloride evaporated to a small volume on a
watch-glass yields upon cooling nice triclinic prisms of so-
dium platinic chloride, Na2PtCl6 + 6Aq, which, on solution
in alcohol, must not leave any residue of potassium platinic
chloride.*
SODIUM
Sodium, which when kept under mineral oil has be-
come covered with a crust, is easily purified by immersing
in a mixture of amyl alcohol (i part) and petroleum (3
parts) and rubbing with a rag soaked in the same mixture
until it acquires a silvery lustre. It is then laid in petro-
leum containing 5 per cent, of amyl alcohol, washed with
pure petroleum and kept in petroleum containing 0.5 to 1
per cent, of amyl alcohol. The bright metal becomes
slowly covered with a film of sodium of amyloxide, which
is, however, easily rubbed off with filter paper. Potassium
and lithium can be purified in the same way and thus
keep their metallic lustre for a long time.
* On an average 12 g. crystallized barium chloride are used. As the
conclusion of the reaction is only recognized with difficulty, in the muddy
solution, you can take here, as in many other cases, conveniently small
samples from the top of the liquid by dipping in a fine capillary tube. The
capillary is blown out on to a watch-glass. In the present case the watch-
glass is placed on a black support and tested with a drop of BaCl2 solution.
which will form BaS04 if H2S04 be present.
INORGANIC PREPARATIONS. 47
Sodium cleaned, as above, combines at once with mer-
cury with evolution of light. The liquid alloy of sodium
and potassium is easily prepared by pressing together the
two clean metals under a mixture of amyl alcohol (i part),
and petroleum (9 parts). Sodium sulphide is also easily
prepared by rubbing the clean metal (1 gram) and salt 3
grams) to a fine powder, and then mixing with sulphur
(0.7 gram), care being taken to avoid any pressure. When
the two substances are intimately mixed, combination sud-
denly takes place with evolution of light. If the mixture
of sodium powder and salt be mixed with sulphur in the
proportions required to form the di- or tri-sulphide, the re-
action takes place more quickly and violently.
Selenium and tellurium behave in the same way as sul-
phur when mixed with sodium powder.*
SODIUM AMALGAM.
(10%).
Heat 3 kilos of mercury in a covered iron pot and
gradually add 300 grams of sodium, in pieces of about
5 grams each. On the addition of each piece of
sodium there is a violent action; toward the close of the
operation it is usually necessary to increase the heat and
stir the mass to produce this reaction. It is not advisable
to clean the sodium, as the oxide is reduced during the
operation and loss avoided. (During the operation glasses
should be worn to protect the eyes.)
* By M. Rosenfeld, Ber. 24, 1658.
48 LABORATORY MANUAL OF
When no further reaction takes place after stirring, the
melted mass is poured out on a clean iron plate, broken as
soon as solid and while still warm, packed in small tightly
closing glass-stoppered bottles.
Sodium Amalgam is used as a means of generating
small quantities of hydrogen for reducing purposes. (See
Hydrogen, page 9).
SODIUM CARBONATE.
(Na3C03 + lOAq.)
It is best to provide this salt in several grades of
purity, as follows :
a. Free from sulphur and chlorine. Finely pulverize
" bicarbonate of soda " of commerce, put the powder into
a funnel stopped loosely with some cotton, make the sur-
face even, cover it with a disk of thick filter paper with
turned- up edges, and wash by pouring small quantities of
water on the paper disk until the filtrate, when acidified
with nitric acid, is not rendered turbid by solution of silver
nitrate, nor by solution of barium chloride. Let the salt
dry, and then convert it by gentle ignition into the simple
carbonate. This is effected best in a vessel of silver or
platinum ; but it may be done also in a perfectly clean
iron, or, on a small scale, in a porcelain dish.
b. Free from silica. The salt, as prepared in a, is liable
to contain silica as well as sand and dirt. To purify it
further, dissolve in twice its weight of water, or dissolve
"sal soda" crystals in their own weight of water, filter, and
pass into the cold solution washed pure carbon dioxide,
but not to complete saturation.
INORGANIC PREPARATIONS. 49
The crystals of hydrogen sodium carbonate that sep-
arate are drained in a funnel, washed with cold water,
dried, and gently ignited, as above directed, as long as
water is given off. Prepared in glass vessels by this
method, sodium carbonate may be readily procured con-
taining but fooo of silica.
c. To a clear and cold solution of 145 grams of sal
soda crystals in 1 00 c. c. of water, add gradually with vig-
orous stirring a solution of 60 parts of purified oxalic acid
in 100 c. c. of warm water. When sodium oxalate ceases
to separate, break up the crystals, and transfer them to a
6-inch filter connected with the Bunsen filter pump, wash
with 500 c c. of water and dry. Heat to full redness in a
platinum dish until the oxalate is fully decomposed, dis-
solve, filter, and evaporate to dryness.*
Sodium carbonate must be perfectly white. Several
grams of the salt must dissolve in water without turbid-
ity, and if the salt is to be used in a flux, without
leaving any residue. Its solution, after supersaturation
with nitric acid, must not be rendered turbid by ba-
rium chloride or silver nitrate; nor must addition of potas-
sium sulphocyanate impart a red, or warming with
ammonium molybdate and nitric acid a yellow tint to it,
or give a yellow precipitate ; the residue which remains
upon evaporating its solution to dryness, after previous
supersaturation with hydrochloric acid, must leave no resi-
due (silica) when redissolved in water. When fused in a
glass tube with potassium cyanide for a long time in a cur-
rent of carbon dioxide, it should give no trace of a dark
sublimate (arsenic).
* J. Lawrence Smith.
50 LABORATORY MANUAL OF
POTASSIUM CYANIDE.
KCN.
Heat potassium ferrocyanide of commerce (perfectly
free from potassium sulphate) gently, with stirring,
until the water of crystallization is completely expelled ;
triturate the anhydrous mass, and mix 8 parts of the
dry powder with 3 parts of perfectly dry potassium car-
bonate ; fuse the mixture in a covered Hessian, or, bet-
ter still, in a covered iron crucible, until the mass is in a
faint glow, appears clear, and a sample of it, taken out
with a heated glass or iron rod, looks perfectly white.
Remove the crucible now from the fire, tap it gently, and
let it cool a little until the evolution of gas has ceased ;
pour the fused potassium cyanide into a heated, tall,
crucible-shaped vessel of clean iron or silver, or into a
moderately hot Hessian crucible, with proper care, to pre-
vent the running-out of any of the minute particles of iron
which have separated in the process of fusion and have
subsided to the bottom of the crucible. Let the mass
now slowly cool in a somewhat warm place. The potas-
sium cyanide so prepared is exceedingly well adapted for
analytical purposes, although it contains potassium car-
bonate and cyanate, which latter is upon solution in water
transformed into ammonium carbonate and potassium car-
bonate 2CNOK + 4H20 = K3C03 + (NH4)2C03). Keep
it in the solid form in a well-stoppered bottle.
Potassium cyanide must be of a milk-white color
and quite free from particles of iron or charcoal. It
must completely dissolve in water to a clear fluid. It
INORGANIC PREPARATIONS. 5 I
must contain neither silica nor potassium sulphide ; the
precipitate which lead salts produce in its solution must
accordingly be of a white color, and the residue which
its solution leaves upon evaporation, after previous super-
saturation with hydrochloric acid, must completely dissolve
in water to a clear fluid.
POTASSIUM SULPHOCYANIBE.
KCNS.
Mix together 46 parts of anhydrous potassium
ferrocyanide, 17 parts of potassium carbonate, and 32
parts of sulphur ; introduce the mixture into an iron
pan provided with a lid, and fuse over a gentle fire ;
maintain the same temperature until the swelling of the
mass which ensues at first has completely subsided and
given place to a state of tranquil and clear fusion ; in-
crease the temperature now towards the end of the opera-
tion, to faint redness, in order to decompose the potas-
sium thiosulphate which has been formed in the process.
Remove the half- cooled and still soft mass from the
pan, crush it, and boil repeatedly with alcohol of from
80 to 90 per cent. Upon cooling, part of the potassium
sulphocyanide will separate in colorless crystals ; to obtain
the remainder, distil the alcohol from the mother liquor.
Solution of potassium sulphocyanide must remain
perfectly colorless when mixed with perfectly pure dilute
hydrochloric acid.
52 LABORATORY MANUAL OF
HYDROGEN SODIUM SULPHITE.
HNaSOg.
Heat 5 parts of copper tacks or clippings with
20 parts of concentrated sulphuric acid in a flask,
and conduct the sulphur dioxide gas evolved, first
through a washing bottle containing some water, then
into a flask containing 7 parts of clean crystallized sal-
soda, and from 20 ' to 30 parts of water, and which is
not much more than half full ; continue the transmission
of the gas until the evolution of carbon dioxide ceases.
Keep the solution, which smells strongly of sulphurous
acid, in a well-stoppered bottle.
Acid sodium sulphite, when evaporated to dryness
with pure sulphuric acid, must leave a residue, the aque-
ous solution of which is not altered by hydrogen sulphide,
nor precipitated yellow by heating with a solution of
ammonium molybdate mixed with nitric acid.
POTASSIUM NITRITE,
KN03.
In an iron pan fuse 1 part of nitre then add 2 parts
of lead, continually stirring with an iron rod. Even
at a low red heat the lead becomes for the most
part oxidized and converted into a yellow powder To
oxidize the remainder, the heat is increased to visible
redness and maintained at that point for half an hour
Allow to cool, treat with cold water, filter and pass car-
INORGANIC PREPARATIONS. 53
bon dioxide through the filtrate. This precipitates al-
most the whole of the lead in solution, the remainder is
removed with a little hydrogen sulphide. Evaporate the
clear fluid to dryness, finally with stirring, and fuse in
order to destroy any potassium thiosulphate. — (Aug.
Stromeyer.) When required, dissolve I part in 2 parts
of water, neutralize cautiously with acetic acid, and filter.
Potassium nitrite must, upon addition of dilute sul-
phuric acid, copiously evolve nitrogen dioxide gas.
SODIUM AND POTASSIUM NITRITE.
A very sensitive surface of spongy platinum is ob-
tained by soaking asbestos yarn in a solution of platinum
oxalate, made by heating freshly prepared platinic chloride
at 204° C, until no more chlorine is evolved, then boiling
the residue with a slight excess of sodium carbonate,
finally dissolving it in oxalic acid, and concentrating the
solution. The soaked asbestos yarn, after drying and
igniting, is exposed to a current of ammonia and air in a
combustion tube, the remote end being heated by a Bun-
sen burner to start the reaction ; the whole platinized sur-
face soon becomes intensely hot, while dense clouds of
ammonium nitrite rapidly form, and are conducted into
sodium or potassium hydroxide, where the corresponding
nitrite is formed, the evolved ammonia being used for pro-
ducing a further supply of ammonium nitrite,*
* By H. N. Warren, (Chem. News, 63, 294).
54 LABORATORY MANUAL OF
POTASSIUM PYROANTIMONATE.
H3K3Sb2076H30.
Introduce a mixture of equal parts of pulverized
tartar-emetic and potassium nitrate in small portions
at a time into a red-hot crucible. After the mass
has deflagrated, keep it at a moderate red heat for a quar-
ter of an hour ; it froths at first, but after some time it will
be in a state of calm fusion. Remove the crucible from
the fire, let the mass get nearly cold, and extract it
with warm water. Transfer to a suitable vessel, by rinsing,
and decant the clear fluid from the heavy white powder
deposited. Concentrate the decanted fluid by evaporation.
After one or two days a doughy mass will separate. Treat
this mass with three times its volume of cold water, work-
ing it at the same time with a spatula. This operation will
serve to convert it into a fine granular powder, to which
add the powder from which the fluid was decanted, wash
well with boiling water, till the washings cease to be alka-
line, and dry on blotting paper, ioo parts of tartar-emetic
give about 36 parts of the pyroantimonate Brunner).
AMMONIUM MOLYBDATE.
CNH4)2MoG4,
Dissolved in Nitric Acid.
Molybdic Solution.
Triturate molybdenum sulphide with about an equal
bulk of coarse quartz sand washed with hydrochloric
acid, until it is reduced to a moderately fine pow-
INORGANIC PREPARATIONS. 55
der ; heat to faint redness, with repeated stirring, until
the mass has acquired a lemon-yellow color (which after
cooling turns whitish). With small quantities this opera-
tion may be conducted in a flat platinum dish, with large
quantities in a muffle. Extract with solution of ammonia,
filter, evaporate the filtrate, heat the residue to faint red-
ness until it appears yellow or white, and then digest for
several days with nitric acid in the water bath, in order to
convert any phosphoric acid present to the tribasic state.
When the nitric acid is evaporated dissolve the residue in
4 parts of solution of ammonia, filter rapidly, and pour the
filtrate into 15 parts by weight of nitric acid of 1.20 specific
gravity. Keep the mixture standing several days in a
moderately warm place, which will cause the separation of
any remaining traces of phosphoric acid as ammonium
phosphomolybdate. Decant the colorless fluid from the
precipitate, and keep it for use. Heated to 400 C. no white
precipitate (molybdic acid or an acid salt of the same) will
separate ; but above that point precipitation will take place
unless more nitric acid be added (Eggertz).
AMMONIUM CHLORIDE.
NH4CI.
Select sublimed white sal ammoniac of commerce.
If it contains iron it must be purified by slowly pass-
ing chlorine gas into the nearly saturated solution for a
short time or until potassium ferricyanide ceases to give a
blue color with a few drops of the liquid. Ammonia is then
added in slight excess, the whole is warmed, filtered from
the separated ferric oxide and evaporated to crystallization
56 LABORATORY MANUAL OF
Solution of Ammonium Chloride must leave no fixed
residue upon evaporation on platinum, and ammonium
sulphide must have no action upon it. Its reaction must
be perfectly neutral.
SODIUM NITRATE.
NaNOs.
Neutralize pure nitric acid with pure sodium car-
bonate exactly, and evaporate to crystallization. Dry the
crystals thoroughly, triturate and keep the powder for use.
A solution of sodium nitrate must not be made turbid
by solution of silver nitrate or barium nitrate, nor precipi-
tated by sodium carbonate.
MONO SODIUM PHOSPHITE.
2NaHP03 + 5H20.
Is obtained by adding sodium hydroxide or carbonate
to phosphorous acid until the solution is neutral to methyl
orange. The liquid is then concentrated by evaporation
and the salt crystallizes. Not unfrequently a supersatur-
ated solution is obtained, which crystallizes in contact
with a fragment of the solid phosphite. If no crystals of
the phosphite are at hand, the solution is concentrated un-
til it has the composition of the crystals and is cooled to a
low temperature. The salt is recrystallized from water
and dried by exposure to air. It can also be obtained by
the action of phosphorus trichloride on sodium carbonate,
but the separation of the sodium chloride is difficult.
INORGANIC PREPARATIONS. 57
Monosodium phosphite is very soluble in water and melts
at 420 C. At ioo° C. the fused salt loses water and the
liquid deposits crystals which may be either a lower
hydrate or the anhydrous salt. If heated at lOO9 C. for
a long time, it becomes completely dehydrated ; it also
becomes anhydrous in a dry vacuum. When heated
above 1309 C. the phosphite changes into sodium pyro-
phosphate.
Potassium phosphite is obtained in a similar manner.
It forms anhydrous crystals, which are difficult to purify by
recrystallization.
POTASSIUM CHLORATE.
KCIO3.
100 grams potassium carbonate are dissolved in warm
water in a small flask heated to boiling, and chlorine is
conducted through the liquid until it is no longer alkaline.
Then dilute with hot water up to a volume of 350 c. c, fil-
ter and let it crystallize.
As a test a weighed sample of the dried salt put in a
covered platinum dish is heated first on the gas furnace,
then on the Bunsen burner with a small flame to incipient
redness; the uncovering of the hot dish must be avoided.
3K2C03+6Cl = KC103 + 5KCl-r-3C02.
The potassium chloride remains in the mother liquor. On
heating the potassium chlorate, the perchlorate first forms,
then the chloride and this finally volatilizes at red heat.
58 LABORATORY MANUAL OF
SODIUM BISULPHATE.
NaHS04.
Mix 7 parts of pure sodium sulphate (obtained by
recrystallizing clean Glauber's salt, and then removing
the water of crystallization at a gentle heat) with 5 parts
of pure concentrated sulphuric acid, in a platinum dish or
large platinum crucible, heat to low redness till the mass
is in a state of calm fusion, then pour out into a platinum
dish placed in cold water, or upon a piece of porcelain,
break the cake into smaller pieces and keep for use.
The sodium disulphate must dissolve in water with
ease to a clear fluid with a strong acid reaction. The
solution must not be rendered turbid or precipitated by
hydrogen sulphide or by ammonia and ammonium sul-
phide.
HYDROGEN SODIUM AMMONIUM PHOSPHATE.
NaHNH4P04.
a. Heat to boiling 6 parts of hydrogen disodium
phosphate and I part of pure ammonium chloride with 2
parts of water, and let the solution cool. Free the crys-
tals produced, from the sodium chloride which adheres to
them, by recrystallization, with addition of some solution
of ammonia. Dry the purified crystals, pulverize and keep
for use.
b. Take 2 equal parts of pure tribasic phosphoric acid,
and add solution of soda to the one, solution of ammonia
INORGANIC PREPARATIONS. 59
to the other, until both fluids have a distinct alkaline reac-
tion ; mix the two together, and let the mixture crystal-
lize.
Hydrogen sodium ammonium phosphate dissolves
in water to a fluid with feebly alkaline reaction. The
yellow precipitate produced in this fluid by silver ni-
trate must completely dissolve in nitric acid. Upon fusion
on a platinum wire, microcosmic salt must give a clear and
colorless bead.
POTASSIUM FERRIC YANIDE.
K6Fe2Cyi2.
Conduct chlorine gas slowly into a solution of I part
of potassium ferrocyanide in 10 parts of water, with
frequent stirring, until the solution exhibits a fine deep
red color by transmitted light (the light of a candle
answers best), and a portion of the fluid produces no
longer a blue precipitate in a solution of ferric chloride,
but imparts a brownish tint to it. Evaporate the fluid
in a dish to y^ of its weight, and allow to crystallize. The
mother liquor will upon further evaporation yield a second
crop of crystals equally fit for use as the first. Dissolve
the whole of the crystals obtained in 3 parts of water, filter
if necessary ; evaporate the solution briskly to half its vol-
ume, and let crystallize again. The solution, as already
remarked, must produce neither a blue precipitate nor a
blue color in a solution of ferric chloride. As this salt de-
composes when long kept in solution, it is best preserved
and applied in the state of powder.
6o LABORATORY MANUAL OF
POTASSIUM IODIDE.
KI.
6 grams pure iron powder are suspended in a small flask
with 50 c. c. water, 25 grams iodine are gradually added,
keeping the mixture cold. At the end of the reaction there
must still be present a slight excess of iron. The solution
is filtered off from the residue, washed with a little water,
and 5 grams iodine added to the filtrate. Now 16.5 grams
potassium carbonate are dissolved in a porcelain dish with
50 c. c. hot water, and the ferrous iodide solution added to
this boiling mixture. Ferrous l^drate separates and car-
bonic acid is freely evolved ; filter and evaporate to crystall-
ization.
By the above process a mixture of ferrous and ferric
iodides is formed, and this by decomposition with alkali
yields ferrous oxide, which is readily removed by filtration.
The potassium iodide in sulphuric acid solution must
not turn starched paper blue, and must be free from
bromine and chlorine.
POTASSIUM CYANATE.
KCNO.
Commercial potassium ferrocyanide is broken in pieces,
dehydrated in an iron dish on a gas furnace and finely
powdered. 200 grams of the anhydrous salt are thor-
oughly mixed with 150 grams potassium dichromate which
has been freed from adhering moisture by fusing on the
INORGANIC PREPARATIONS. 6l
gas stove. The mixture is placed into a capacious iron
dish in portions by means of a spoon, and heated to such
an extent over a Bunsen burner or gas stove that every
portion of the powder added is converted into a black
mass. Stir with an iron spatula while putting the mixture
into the dish. The temperature must not rise high enough
to cause fusion of the mass. After cooling, the porous
mass is powdered, put into a flask with I litre of 80%
boiling alcohol, shaken and boiled for five minutes,
with reversed condenser. After settling, pour off the clear
solution into a beaker, which is set in cold water to cool,
whereupon the potassium cyanate, especially by stirring
with a glass rod, precipitates in a heavy white crystallized
powder. The mother liquor serves for further (3d or 4th)
extraction of the black product.
K4Fe(CN)6+ 2K2Cr307 = 6KCNO + 2Cr203 + FeO + K30.
The unaltered potassium ferrocyanide remains in-
soluble on recrystallization from alcohol. The hot
solutions must be cooled quickly, as by heating any length
of time, the water contained in the diluted alcohol would
decompose the cyanate.
KCNO + 2H20 = K(NH4)C03.
Analyze the salt by evaporating a sample with cone,
sulphuric acid and fusing the remaining potassium sul-
phate with addition of a grain of ammonium carbonate.*
C. A. Bell, Chem. News, 32, 99.
62 LABORATORY MANUAL OF
POTASSIUM COBALTIC OXALATE.
K6Co3(C304)6 + 6H30.
Is obtained by mixing cobaltic hydroxide, potassium
oxalate, oxalic acid and water to a thick paste, and allow-
ing the mixture to stand from 1 4 to 2 1 days. After recry stall-
ization, the salt is obtained in nearly black, well-formed,
seemingly monosymmetric crystals, which in thin lamellae
show distinct dichroism (dark-blue and emerald-green).*
When treated with cold saturated sodium chloride solu-
tion, the sodium potassium salt is obtained, crystallizing in
beautiful pyramids.
POTASSIUM METANTIMONATE.
K4Sb3Or.
100 grams of black sulphide of antimony, 1 50 grams of
potassium carbonate, IOO grams of slaked lime and 20
grams of sulphur, are shaken with 1 2 liters of water and
after standing eight days the mixture is filtered. The fil-
trate, which contains potassium sulphantimonate, is boiled
with 120 grams of copper oxide and filtered. The filtrate
is diluted with water and treated with carbonic anhydride,
when potassium metantimonate is precipitated.!
* F. Kehrmann, Ber., 19, 3101.
f Duyk, Bull. Soc. Roy. Pharm., Bruxelles, 37, 109.
INORGANIC PREPARATIONS. 63
CRYSTALLINE NORMAL LITHIUM PHOS-
PHATE and ARSENATE.
Fused lithium chloride dissolves the amorphous, normal
phosphate, and on cooling and washing the melted mass,
rhomboidal, tabular crystals of normal lithium phosphate,
which have a sp. gr. 2.41 at 150 C, and are infusible at a
white heat, are obtained. The normal arsenate is similarly
prepared ; it corresponds with the phosphate physically,
and is of sp. gr. 3.07 at 150 C*
PREPARATION OF PURE CAESIUM AND
RUBIDIUM COMPOUNDS
Preparation of pure caesium and rubidium salts from
their minerals is carried out as follows : They are first
separated in the form of the double salts with lead tetra-
chloride ; the latter is decomposed with water, the solu-
tion treated with a slight excess of ammonium sulphide to
free it from lead, and the filtrate evaporated to dryness ;
the mixed chlorides of caesium and rubidium are dissolved
in concentrated nitric acid, the solution evaporated to dry-
ness, the residue dissolved in water, excess of oxalic acid
added, and the mixture again evaporated to dryness, and
heated in a platinum crucible until the oxalates are com-
pletely converted into carbonates. The rubidium is then
separated as acid tartarate and the caesium as caesium
antimony chloride. t
* By A. DE Shulten, Bull. Soc. Chera. [3], 1, 479.
f By H. L. Wells, Amer. J. Sci., 46, 186.
64 LABORATORY MANUAL OF
PREPARATION OF PURE RUBIDIUM SALTS.
Commercial " pure " rubidium salts contain small quan-
tities of caesium and potassium, which it is difficult to detect
by means of the spectroscope. To obtain a pure salt, com-
mercial rubidium chloride (30 grams) is dissolved in very
strong hydrochloric acid (250 c. c.) and antimony chloride
(2.5 grams) dissolved in strong hydrochloric acid is added.
The small precipitate (about 1.4 grams Rb, SbCl4 and
CsSbCLt) is filtered off on an asbestos filter, the filtrate
evaporated almost to dryness, the antimony still present
removed with hydrogen sulphide, and the resulting mix-
ture dissolved in strong hydrochloric acid. Rather more
of a hydrochloric acid solution of stannic chloride is added
than is necessary to form the stannic chloride, Rb2SnCl6 ;
this substance is then precipitated, whilst potassium stannic
chloride, K3SnCl6, remains in solution. The precipitate is
allowed to settle, washed several times by decantation, col-
lected on an asbestos filter, dissolved in water, and the tin
removed with hydrogen sulphide. The rubidium chloride
so obtained is pure, 0.44 gram contains 29.30 instead of
29.34 per cent, of chlorine.*
PREPARATION OF TUNGSTATES FREE
FROM MOLYBDENUM.
Commercial tungstates and tungstic acid contain vary-
ing quantities of molybdenum. After several unsuccessful
attempts to get rid of this impurity, the following method
By W. Muthmann, Ber. 26, 1019-1020.
INORGANIC PREPARATIONS. 6$
was found to give the desired result. Sodium tungstate,
prepared in the usual way, is dissolved in cold water, and
to the saturated solution hydrochloric acid is added until
the reaction is only feebly alkaline ; the paratungstate thus
obtained is crystallized out and once recrystallized. One-
half of it is dissolved in boiling water, and hydrochloric
and a little nitric acid added ; hydrated tungstic acid is
precipitated. This is washed thoroughly with hot water
and added to a boiling solution of the other half of the
paratungstate, until a portion no longer gives a precipi-
tate with hydrochloric acid. The bulk of the solution is
then filtered, hydrochloric acid is added, and the solution
is boiled and repeatedly saturated with hydrogen sulphide.
This precipitates the molybdeum as sulphide, whilst the
metatungstate is not attacked. The solution is filtered,
concentrated, oxidized with a few drops of bromine water,
and neutralized with soda ; pure sodium paratungstate
can then be obtained from it by crystallization. To ob-
tain the potassium and ammonium salts, the acid should be
prepared by adding hydrochloric acid to the sodium salt,
and then neutralize with potash or ammonia.
An analysis of sodium paratungstate thus prepared
agreed better with the formula 5Na30, 12W03, 28H20
than with 3Na20. 7W03, 16H20.*
TITANIUM TRIOXIDE.
Ti03.
Pure titanium chloride is added drop by drop to dilute
alcohol, and the clear and very dilute solution is treated
* By C. Friedheim and R. Meyer, Zeit. Anorg. Chem. i, 76-81.
5
66 LABORATORY MANUAL OF
with a large excess of hydrogen peroxide. Ammonia, am-
monium carbonate, or aqueous potash, is added to the
solution with the production of a yellow, or in case of
ammonia, of a reddish yellow liquid, which after some time
yields a yellow precipitate. This is allowed to subside,
the clear solution siphoned off, and the precipitate repeat-
edly washed by decantation ; the compound, however,
tends to retain water and salts in considerable quantities.
When dried on a tile it approximates to the composition :
Ti03 + 3H30.*
PREPARATION OF VANADYL TRICHLORIDE.
Extraction of Vanadium from Its Ores.
For the extraction of vanadium from its ores advantage
is taken of the volatility of vanadyl trichloride. The
finely divided mineral is intimately mixed with about
one quarter of its weight of lamp black and a little oil, and
ignited to volatilize the arsenic and zinc. The calcined
product is then slowly heated to 13 i° C. in a stream of dry
chlorine, and the vanadyl trichloride collected in tubes im.
mersed in a freezing mixture. When it is desired to
determine the quantity of vanadium in an ore, the above
method is employed, and the vanadyl trichloride is col-
lected in a series of bulbs containing distilled water ; the
vanadic acid is then reduced with zinc, and estimated volu-
metrically with the aid of potassium permanganate, t
* A. Classen, Ber. 21, 370.
f By L. L'Hote Ann. Chim. Phys. [6], 22, 407-412.
INORGANIC PREPARATIONS. 6j
VANADYL CHLORIDE.
Prepared from vanadianite (14.42% V205) by mixing
the powdered mineral with four times its weight of lamp
black, making into a paste with oil and calcining. The
calcined product is then heated in an oil bath in a current
of dry chlorine, care being taken to prevent the tempera-
ture exceeding 1 3 1 ° C. Pure vanadyl chloride begins to
distill at98° C, and if the temperature is raised to 131 °C.
the whole of the vanadium in the mineral is converted into
this compound.*
AMMONIUM BICARBONATE.
(NH4)HC03.
Pour cone, aqua ammonia into a small flask and close
it with a stopper attached to a short glass tube, through
which carbonic acid is passed. The neutral ammonium car-
bonate which precipitates at first, redissolves, and after the
liquid has for a time been subjected to the carbonic acid,
the acid salt separates. More bicarbonate may be obtained
from the mother liquor by mixing it with alcohol. It is
preserved in glass tubes which are filled with carbonic acid
and sealed.
Ammonium bicarbonate crystallizes in hard, glossy,
rhombic prisms, very readily volatile. The aqueous solu-
tion must not be rendered turbid by the addition of
calcium chloride.
* By L. L'Hote, Compt. Rend. 101-1151.
68 LABORATORY MANUAL OF
AMMONIUM BROMIDE.
NH4Br.
AND
POTASSIUM BROMIDE.
KBr.
From a dropping funnel with a finely drawn out stem
75 c. c. of bromine are allowed to flow, slowly and with con-
tinual shaking, into 220 c. c. of cone. (30%) ammonia con-
tained in a flask cooled with ice-water, taking care that the
liquid shall remain strongly ammoniacal at the end of the
reaction. It is then boiled until the free ammonia has
been driven out and evaporated to crystallization. The
ammonium bromide is dried by gently heating in a porce-
lain dish over an open fire. (2) 196 grams ammonium bro-»
mide are dissolved in hot water, 200 grams potassium
bicarbonate added, and the whole is heated to boiling ;
when the ammonia has been driven out it is allowed
to crystallize :
4NH3+3Br=3NH4Br+N.
If the solution should become acid, or the bromine
flow in too rapidly, there might be a formation of nitrogen
bromide which would cause an explosion.
As a test a small sample of the salt is boiled in a re-
tort with a large excess of iron-ammonia alum in aqueous
solution, whereby any iodine which may be present will
pass over in a free state ; remove the bromine from the
residue by addition of potassium permanganate solution
and test for chlorine. This separation of the halo-
INORGANIC PREPARATIONS. 69
genes depends on the fact that ferric salts will set free
iodine from neutral solutions of the iodides :
Fe3(S04)3 + 2KI = 2FeS04 +■ K2SO4 + 21.
while the bromides remain unchanged.
On the other hand, these are also entirely decomposed
if a small quantity of a strong oxydizing agent (perman-
ganate) is present. The chlorides resist the simultaneous
influence of these two agents.
PREPARATION OF AMMONIUM PERSULPHATE.
A porous clay cell (80 to 100 c. c. capacity), containing
a saturated solution of ammonium sulphate in a mixture
of I part by volume of sulphuric acid with 8 parts by
volume of water is placed in a beaker and surrounded by
a mixture of equal volumes of sulphuric acid and water.
A lead cylinder, placed round the porous cell, serves as
the carthode and a platinum spiral, having a surface of 0.5
sq. cen., is suspended inside the porous cell to serve as the
anode. The beaker is embedded in ice. The electrolysis
is effected by a current of 2 to 3 amperes ; some 8 volts will
be necessary when the internal resistance of the decom-
posing cell is about I ohm. After 2 to 3 hours the contents
of the porous cell are filtered through glasswool and the
crystals of ammonium persulphate dried on a porous
plate ; the filtrate is shaken with ammonium sulphate and
once more electrolysed. 20 to 40 grains of the persulphate
may thus be obtained in one operation, the yield being
least at the outset, when the liquor is being saturated
JO LABORATORY MANUAL OF
with the persulphate. The sulphuric acid in the outer
cell eventually becomes alkaline from the transit of the
ammonium, and pari passu the ammonium sulphate
in the inner cell becomes strongly acid ; from time to
time the former liquid must be renewed and the latter
nearly neutralized with ammonia. To recover the per-
sulphate left in the liquor when the preparation has been
completed a concentrated solution of potassium carbonate
or acetate is added ; potassium persulphate will thus be
precipitated, as 100 parts of water only dissolve 2 parts of
this salt, whereas they dissolve 65 parts of the ammonium
salt*
Ammonium persulphate thus prepared contains some
3 to 5 per cent, of impurities, consisting chiefly of ammo-
nium sulphate, but partly of ammonium alum, derived
from the clay of the porous cell. It may be recrystallized
from water.
AMMONIUM DICHROMATE.
(NH4)2Cr207.
Chrome iron ore is heated with sodium or potassium
salts ; the resulting monochromate is dissolved in water,
treated with 2 equivalents of acids, and then neu-
trallized with ammonia or ammonium carbonate. The
solution containing a dichromate and sulphate, chloride,
or nitrate, as the case may be, is concentrated ; the latter
salts as they crystallize are removed, and finally on cool-
By K. Elbs, J. pr. Chem. [2] 48, 185-189.
INORGANIC PREPARATIONS. 7 1
ing ammonium dichromate crystallizes out. The potas-
sium or sodium salts are used again for heating with fresh
chrome iron ore.*
AMMONIUM NITRITE.
NH4N02.
The mixture of nitrogen oxides evolved during the
action of arsenious anhydride or nitric acid is passed over
coarsely powdered ammonium carbonate kept cool by
ice. The half liquid mass is treated with alcohol, the
unchanged carbonate filtered off, and the ammonium nitrite
precipitated by means of ether. The nitrite so obtained
is of 90 to 94 per cent, purity, and may be purified by
resolution in 96 per cent, alcohol and reprecipitation
with ether. Pure ammonium nitrite forms almost color-
less needles, which are deliquescent and dissolved in water
with development of heat. It is easily but slowly soluble
in alcohol, and is precipitated from this solution by ether,
chloroform or ethyl acetate. Concentrated solutions appear
to decompose with explosive violence at 6o° to 700 C.f
like the solid salt, and in acid solutions, such decomposi-
tion sometimes occurs at ordinary temperatures. The dry
salt may be safely kept in an atmosphere of hydrogen and
in presence of pieces of ammonium carbonate and of lime.
It is best kept and transported under absolutely dry and
alcohol free ether. t
* T. J. Hood, Chem. Zeit. 11, 55.
f S. P. L. Sorensen, Zeit. anorg. Chem., 7, 33.
72 LABORATORY MANUAL OF
AMMONIUM DI HYDROGEN PHOSPHITE.
NH4H2PO3.
A solution of phosphorous acid mixed with ammonia
until neutral to methyl orange, and then concentrated
until the weight of the liquid is one-fourth or one-fifth
more than the calculated weight of the salt, yields large
deliquescent crystals, which can be dried over sulphuric
acid or at ioo° C. Similar crystals are obtained if the
liquid is concentrated in vacuo at ordinary temperature.
The crystals have the composition NH4H2P03, and seem
to be monoclinic prisms; they melt at 1230 C. and are
very soluble in water. At 1450 C. they lose half their
ammonia without evolution of hydrogen phosphide and
yield a gummy mass which seems to contain crystals.
At a higher temperature ammonia and hydrogen phos-
phide are given off and phosphoric acid is formed.*
AMMONIO ZINC CHLORIDES.
If a stream of ammonia is passed into a hot concen-
trated solution of zinc chloride until the precipitate first
formed is redissolved, and the whole is then allowed to
cool, nacreous scales of the composition ZnClg, 4NH3 + H20
crystallize out. On concentration the mother liquor yields
crystals of the formula ZnCl3, 2NH3; this compound
separates in colorless rhombic crystals, which do not
* L. Amat. Compt. Rend., 105, 809.
INORGANIC PREPARATIONS. 73
change on exposure to air. It is insoluble in water, but
when boiled with it decomposes with evolution of am-
monia. It is easily soluble in solutions of ammonia or
ammonium chloride. The same compound is also formed
when ammonia is added to a cold dilute solution of zinc
chloride until the precipitate first formed is redissolved, or
when freshly precipitated zinc hydroxide is dissolved in
a concentrated solution of ammonium chloride. The same
compounds, in well formed crystals, has also been found
in Leclanche cells. The constitution is probably expressed
by the formula NH8Cl.Zn.NH3CL*
CUPROUS CHLORIDE.
CuoCte.
Cuprous chloride can be conveniently prepared by
heating a mixture of copper sulphate (4 grams) and so-
dium hypophosphite (2 grams) in about 50 c. c. of
water to which 30 drops of fuming hydrochloric acid are
added.
The cuprous chloride is deposited and can be purified
in the ordinary way. The change can be explained thus :
Copper hypophosphite is at first formed, and this is con-
verted by the hydrochloric acid into cuprous chloride and
phosphoric acid. The equation is as follows : 2CuCl2 -f
H3P03 4- H20 = H3P03 + 2HC1 + Cu3Cl2.
Another method of preparation is to pour 100 c. c.
hot water over 42 grams copper chloride (cryst.) and
32 grams metallic copper (granulated or turnings) ; add
* H. Thomas, Ber., 20, 743.
74 LABORATORY MANUAL OF
200 c. c. crude hydrochloric acid (sp. gr. 1.175), and boil
gently in a flask closed by a small funnel ; finally add a
little fuming hydrochloric acid and boil until the solution
becomes colorless. This operation lasts one to two hours,
but can be hastened considerably if the copper powder in
cakes obtained in preparing blue vitriol is added to the
solution. The colorless solution is poured off from the
surplus copper into a cylinder filled with cold distilled
water, the cheesy precipitated protochloride is allowed to
settle and decanted immediately, quickly filtered, washed
with ether and alcohol, and dried in vacuum over sul-
phuric acid.
CuCl2 + Cu = Cu3Cl2.*
Cuprous chloride forms in heavy white masses, insolu-
ble in water, and oxydizes easily in the air and, with
chlorine water or aqua regia (nitromuriatic acid), dissolve
readily as copper chloride. By heating in small tubes
the protochloride melts without decomposition.
CUPROUS CYANIDE.
(Cu2CN)2.
50 grams crystallized blue vitriol are dissolved in 300
c. c. hot water, and to this hot solution in a flask, add,
by means of a dropping funnel, a solution of 26 grams
potassium cyanide in 50 c. c. water. The escaping cy-
anogen gas is passed through a glass tube bent upward,
tapering to a point and lighted at the end of the tube as
soon as the apparatus is filled with it. The gas is very
By A Cavazzi, Gazzetta 16, 167-168).
INORGANIC PREPARATIONS. 75
poisonous and burning is a ready way of getting rid of it.
The white cheesy sediment is separated by decanting from
the faintly bluish-colored solution, washed with water and
dried on an earthen plate.
CuS04 + 2KCN = Cu(CN)2 + K2SO,.
2Cu(CN)3 = Cu2(CN)2 + CN2.
Cuprous chloride is a tolerably stable white powder,
similar on the whole to the copper protochloride. Decom-
poses by heating, with a cyanogen odor.
COPPER AMMONIUM SULPHATE.
(NH3)4CuS04.
COPPER POTASSIUM SULPHATE.
CuK2(SO)2 + 6H20.
Ammonium double-salt. — 30 grams blue vitriol are
dissolved in 100 c. c. ammonia-solution of 0,962 sp. gr.
150 c. c. alcohol are then placed into a high, narrow cy-
linder, and by means of a long-stemmed dropping funnel
20 c. c. water are carefully poured into the alcohol ; then
the copper solution is added in a very fine stream, so that
it will gather at the bottom of the cylinder, and is
separated from the alcohol by the water. Upon standing
from 1 to 4 weeks it forms large dark blue crystals.
Potassium double-salt. — 100 grams blue vitriol in a
saturated solution at jo° C. are mixed with a solution of
69,8 grams potassium sulphate and 7 c. c. cone, sulphuric
acid. On cooling the whitish-blue crystals of the double-
salt separate.
Determine the copper value of the salts : Of the am-
76 LABORATORY MANUAL OF
monia double-salt by simply annealing and weighing the
remaining copper oxide; of the potassium double-salt by
precipitating with a piece of cadmium or zinc in a weighed
platinum dish from the diluted solution made faintly acid
with hydrochloric acid. When a sample of the discolored
solution no longer reacts with sulphureted hydrogen water,
rinse with a little hydrochloric acid, then with hot water,
and lastly with alcohol; dry at ioo° C. and weigh.
CUPRIC SULPHATE.
CuS04,5H30.
This reagent may be obtained in a state of great purity
from the residue remaining in the flask in the process of
preparing hydrogen sodium sulphite by treating with
water, applying heat, filtering, adding a few drops of nitric
acid, boiling for some time, allowing to crystalize, rnd
purifying the salt by recrystallization.
After precipitation by hydrogen sulphide, ammonia
and ammonium sulphide must leave the filtrate unaltered.
CUPROUS OXIDE.
Cu20.
A fairly concentrated solution of copper sulphate along
with excess of sodium chloride is thoroughly reduced by
treatment with gaseous sulphurous anhydride ; the excess
of the latter is then expelled by heating, and solid sodium
carbonate is added to the hot solution ; bright red cuprous
oxide is precipitated, and is readily washed by decantation.*
E. J. Russell, Chem. News, 68, 308.
INORGANIC PREPARATIONS. JJ
CUPROUS AMMONIUM IODIDE.
4NH3CU3I4.
IOO grams of an ammoniacal solution of cupric oxide
containing 7 to 8 per cent, is mixed with an equal weight
of a 10 per cent solution of iodine in alcohol. A brown
precipitate of nitrogen iodide is formed, but this readily
disappears on warming, and if the liquid is heated for about
an hour on the water bath it becomes green and deposits
brilliant green needles, which must be dried as quickly as
possible. They have the composition 4NH3,Cu3l4 or
4NH3Cu2l2,CuI2 and alter rapidly when exposed to air,
losing ammonia and iodine, and eventually changing to
cuprous iodide. The crystals are insoluble in water, but
are decomposed by prolonged boiling. They are only de-
composed by potash after prolonged boiling, but they
dissolve readily in ammonia, and the solution yields cu-
prammonium iodide when evaporated. If the green solu-
tion obtained as above is boiled with metallic copper until
it becomes colorless and is then allowed to cool, it deposits
cuprosoammonium iodide in brilliant white needles 5 to 6
mm. long. If the mixture of ammoniacal copper solution
and alcoholic iodine is allowed to stand with exposure to
air at the ordinary temperature, the nitrogen iodide slowly
dissolves, and after some hours the liquid deposits cupram-
monium iodide in octahedral crystals. If the ammoniacal
solution is boiled with iodine for several hours without ad-
dition of alcohol, and is then cooled, it deposits cupram-
monium iodide in tetrahedral crystals.
7% LABORATORY MANUAL OF
CUPROAMMONIUM TETRIODIDE.
4NH3CuI3,I2.
Is obtained in brilliant black crystals, green by trans-
mitted light, by boiling ioo c. c. of the ammoniacal copper
solution with 20 grams of iodine, and allowing the liquid
to cool. If a further quantity of 20 grams of iodine is dis-
solved in the mother liquid from these crystals, the liquid on
cooling deposits cuproammonium hexiodide 4NH3,CuI2I4,
in rectangular tablets, which are brown by transmitted
light. This compound is usually obtained by mixing a
warm solution of cuproammonium nitrate with a solution
of iodine in potassium iodide.
CUPROUS PHOSPHIDE.
Cu3P3.
When red phosphorous is immersed in an ammoniacal
solution of copper sulphate, it becomes coated, as is well
known, with a greyish deposit, which is a mixture of
cuprous phosphide and metallic copper; the same occurs
with an ammoniacal solution of copper phosphate, but the
transformation is never complete, even at iooQ C. If,
however, red phosphorous is heated with a large excess of
copper phosphite and water in a sealed tube for four hours
at 1300 C, its entire conversion is effected. The product
is washed quickly with aqueous ammonia and water in
succession, and dried in a vacuum. If the temperature hac
not exceeded that specified, it is not contaminated with
metallic copper.*
* By A. Granger, Compt. rend., 117, 231-232.
INORGANIC PREPARATIONS. 79
Cuprous phosphide, Cu2,Pg, is a grey powder resembling
plumbago in appearance. It is attacked by chlorine and
bromine in the cold, and is readily dissolved by dilute
acetic acid ; a mixture of it with potassium nitrate or
chlorate detonates violently when struck. When heated
in contact with air, it is oxydized to copper phosphate. It
is decomposed by heat into products identical with those
yielded by cupric phosphide. It is slightly soluble in
hydrochloric acid, yielding a solution from which cuprous
oxide is precipitated by potash, and which, when super-
saturated with ammonia, precipitates metallic silver from
an ammoniacal solution of silver nitrate.
PURE SILVER.
Ag-
a. Crystallized Silver. — Any weighed quantity of
technical silver (coin or broken plate) is dissolved in
nitric acid, filtered and dried. The dried mass is
fused until it begins to turn black, dissolved in water,
filtered and diluted to such a degree that the solu-
tion contains 2 per cent, silver. It is now made
strongly ammoniacal in the cold and sodium bisulphite
solution added until a sample of the blue solution is de-
colorized on boiling. The greater part of the silver
separates in crystals as the solution cools, the remainder
by warming at 6oQ to 709 C. The silver is washed with
water, then digested several times with concentrated am-
monia, again washed with water, dried on the waterbath
and weighed.
b. Molecular Silver from Residues. — Silver residues
together with zinc sticks are boiled with addition of hy^
80 LABORATORY MANUAL OF
drochloric acid. The reduced silver, freed mechanically
from the undissolved zinc, is washed well by decantation,
then dissolved in nitric acid and precipitated with hydro-
chloric acid. The decanted and washed silver chloride is
placed, while still moist, in soda lye, kept boiling in a porce-
lain dish and adding at intervals a few c. c. of cone, grape
sugar solution, until a filtered and washed sample of the
gray silver powder dissolves completely in nitric acid.
Wash, dry and weigh as described in a.
The black color appearing in fusing the impure nitrate
arises from the decomposition of the copper nitrate ;
to avoid any loss of silver it is not heated until all the
copper salt has been converted into oxide ; but the separa-
tion of silver from the copper is so managed that the silver
from the ammoniacal solution is precipitated in metallic
form by sulphurous acid, while the copper, under these
circumstances, is reduced to protoxide, which remains dis-
solved in the ammoniacal solution.
Dissolve a sample of the silver in nitric acid free from
chloride, and note any sediment (gold, silver, chloride, tin
dioxide) ; precipitate the solution with hydrochloric acid
and test the filtrate for heavy metals.
PREPARATION OF PURE COLLOIDAL SILVER.
Solutions of ferrous sulphate (150 grams of the salt in
500 c. c. of the solution) and of sodium citrate (280 grams
of the salt in 700 c. c. of the solution) are mixed and
poured into a 10 per cent, solution of silver nitrate (500
INORGANIC PREPARATIONS. 8 1
c. a). Day-light need not be excluded, but it is ad-
visable to divide the mixture into five equal portions, as
small quantities can be dealt with more easily than large.
At the end of half an hour the supernatant liquid is re-
moved from the precipitated colloidal silver with a pipette,
and the silver is thrown on to a filter (Schleicher and
Schull's No. 590 paper), filtered under diminished pressure,
and dissolved on the filter in the minimum quantity of
water ; solutions may thus be obtained containing 20
grams of silver per litre. To this solution absolute alcohol
is added with agitation until coagulation is perceptible,
and, after remaining for several days, the colloid is fil-
tered under a diminished pressure of 10 to 20 mm. on a
Pasteur filter-tube, when it forms a beautiful iridescent
incrustation. Colloidal silver in this state of purity is
soluble in alcohol, and cannot therefore be washed with
this liquid to remove the last traces of crystalloids. By
this method a product containing only .03 to .05 percent, of
iron is obtained.*
SILVER POTASSIUM CARBONATE.
AgKC03.
150 grams of potassium carbonate are dissolved in 150
c. c. of water, cooled and agitated with 1 5 grams of potas-
sium hydrogen carbonate. When the liquid is saturated
with the latter salt at ordinary temperature, it is filtered
and mixed with a solution of one gram of silver nitrate in
25 c. c. of water. In order to obtain large crystals, the liquid
containing the precipitate is heated with continual agita-
* By E. A Schneider, Ber. 25, 1281-12S4.
6
$2 LABORATORY MANUAL OF
tion. The precipitate dissolves, and when the liquid is
cooled it deposits long, transparent crystals with a brilliant
lustre: sp. gr. 3.769. They do not blacken when exposed
to light except in the presence of organic matter, and when
treated with water the silver carbonate which remains re-
tains the form of the original crystals. When heated the
compound loses carbonic anhydride, and at a higher tem-
perature the silver oxide which is formed gives off oxygen.
The crystals are microscopic, rectangular lamellae with
a terminal angle closely approaching 900. The refraction
is almost identical with that of apatite.*
PURE GOLD.
Au.
Commercial gold (broken pieces of jewelry, a coin or
crude washgold) is broken into pieces as small as possible,
weighed, placed in a small flask and concentrated hydroch-
loric acid poured over it. The flask is heated in a sand-bath,
and from time to time cone, nitric acid dropped into it. After
all is dissolved evaporate in a porcelain dish on the water-
bath, carefully avoiding all dust, until the remaining dark-
red solution solidifies on cooling. Then dissolve in plenty
of water, filter from the separated silver chloride and pre-
cipitate the filtrate hot with ferrous chloride solution in
excess. The separated gold in powder is decanted, boiled
several times with diluted hydrochloric acid, gathered on
an ashless filter, fused in a porcelain crucible and weighed.
In case larger quantities of gold are refined, a little platinum
* A de Schulten, Compt. Rend. 105, 811.
INORGANIC PREPARATIONS. 83
and palladium (even thallium) can be separated from the
filtrate with iron or zinc.
The gold obtained in form of a reddish powder should
not impart a trace of yellowish color (iron) to boiling hy-
drochloric acid. If a weighed quantity is once more
subjected to the refining process described above the
weight should remain constant.
AURIC CHLORIDE, OR GOLD TRICHLORIDE.
AuCl3.
Take fine shreds of gold, which may be alloyed with
silver or copper, treat them in a flask with nitrohydrochloric
acid in excess, and apply a gentle heat until no more of
the metal dissolves, then dilute the solution with 10 parts
of water. If the gold was alloyed with copper — which is
known by the brownish-red precipitate produced by po-
tassium ferrocyanide in a portion of the solution diluted
with water — mix it with solution of ferrous sulphate in
excess. This will reduce the auric chloride to metallic
gold, which will separate in the form of a fine brownish -
black powder ; wash the powder in a small flask, and dis-
solve it in nitrohydrochloric acid ; evaporate the solution
on the waterbath, and dissolve the residue in 30 parts of
water. If the gold was alloyed with silver, the latter
metal remains as chloride, upon treating the alloy with
nitrohydrochloric acid. In that case evaporate the solu-
tion at once, and dissolve the residue in water for use
84 LABORATORY MANUAL OF
AUROSO-AURIC CHLORIDE.
Au2Cl4.
By leading a stream of dry chlorine for 30 minutes
over gold, precipitated from a solution of gold chloride by
sulphurous acid, 50 to JO grams of gold may be converted
into a homogeneous mass corresponding with the formula
AU2CI4. The reaction is started by gentle heating, but the
necessary temperature is then maintained by the heat
evolved in the reaction, provided that cooling is prevented
by surrounding the tube with cotton or glass wool.*
ANHYDROUS MAGNESIUM CHLORIDE.
MgCl2.
500 grams crytallized magnesium chloride and 500
grams sal ammoniac are dissolved in a very small quantity
of water, filtered in a porcelain dish and dried in a silver
dish. The solid mass is broken while hot and dried in
small portions on porcelain or, better, on platinum dishes
(the mixture corrodes base metals, silver also, at a higher
temperature). The operation occupies some time and is
to be carried out with great care, as even very small
quantities of water frustrate the success of the experi-
ment. Dry in portions on several gas stoves and regulate
the heat so that an escape of ammonium chloride vapor does
not take place. Powder the portions from time to time in
a hot mortar, continue drying until the product, on heat-
J. Thomsen, J. pr. Chem. [2] 37, 105.
INORGANIC PREPARATIONS. 85
ing, no longer cakes and only consider the operation
completed when a sample heated in a test tube shows no
moisture ; after driving off the ammonium chloride there
remains a clear solution, forming radiant crystals upon
cooling. Then pour the powder* while still hot in a
spacious platinum crucible, close with a well-fitting cover
and place into the Roessler furnace which has previously
been heated. After the ammonium chloride is driven out,
again fill the crucible t with the loose powder, and con-
tinue heating until the entire mass is fused. The solidified
magnesium chloride, which is easily removed from the
crucible, should be placed in a well-stoppered bottle while
still warm.
Crystallized magnesium chloride can be rendered an-
hydrous and the formation of a basic salt prevented by
heating it in a current of hydrogen chloride.f
Crystallized magnesium chloride on heating loses the
largest quantity of its chlorine in the form of hydrochloric
acid; on the other hand, the double-salt (NH4)2MgCl4
can, by heating carefully, be volatilized without decompo-
sition. On igniting this double-salt anhydrous magnesium
chloride remains.
(NH4)2MgCl4 = MgCl3 + 2NH4C1.
Magnesium chloride crystallizes in large radiant g^ssy
crystals, not unlike fused sodium acetate, which melt readily
on heating and volatilize at red-heat. The vapors decom-
* If the dried substance is to be preserved, this must be done in well-
stoppered vessels. Before using the mass it should be dried for a short time
on the gas stove.
f When in a red-hot condition the crucible must not be opened on
account of the volatility of the magnesium chloride.
% W. Hempel, Ber. 21, 897.
86 LABORATORY MANUAL OF
pose aqueous vapor instantly, forming hydrogen chloride.
The very hydroscopic salt should form a clear solution in
warm water.
CRYSTALLIZED NORMAL MAGNESIUM CAR-
BONATE.
MgC03 + 3 H20.
If freshly precipitated magnesium carbonate, made by
mixing equivalent amounts of magnesium sulphate and so-
dium carbonate,is shaken with a solution of potassium hydro-
gen carbonate at the ordinary temperature, much of the mag-
nesium carbonate dissolves, crystallizes out of the filtered
solution after a time ; the separation is ended in 24 hours.
The same occurs if sodium hydrogen carbonate is used ; it
dissolves relatively more of the magnesium carbonate, but
the crystals obtained are smaller. Solutions containing
respectively 67.5 grams of potassium and 12.96 grams of
sodium hydrogen carbonate per liter dissolved, respectively,
18.73 and 9.95 grams of magnesium carbonate. The crys-
tals have the composition 4MgCo3 + 15H30 ; after four
weeks in dry air, or 1 5 hours in a vacuum dessicator
over sulphuric acid, they have the composition 2MgC03 -f
6H20; after heating at 1700 C. the composition MgCOg -f
a/3 — VgHgO. The reaction is that a double sesquicarbonate
of magnesium and the alkali metal is formed, and that this
afterwards decomposes, magnesium carbonate being pre-
cipitated, and carbonic anhydride liberated, which latter
regenerates the alkali bicarbonate with the alkali sesqui-
carbonate now present.
Alkali bicarbonates do not dissolve calcium carbonate
INORGANIC PREPARATIONS. 87
or ferric hydroxide, and upon this fact a technical process
for the preparation of pure magnesium carbonate from
dolomite, magnesite, bitterspar and from kanite or caen-
allite liquors has been based. The mineral is powdered,
dissolved in commercial hydrychloric acid and the iron
oxydized by warming gently with a little nitric acid. The
solution is then precipitated with sodium carbonate in slight
excess, the filtered precipitate shaken with a sufficiently
strong solution of alkali bicarbonate, and the solution fil-
tered after a lapse of 20 minutes and set aside to crystal-
lize. The mother liquor can be used repeatedly for the
extraction.*
MAGNESIUM BASIC CARBONATE.
Mg(OH)2,MgC03.
Prepare a strong solution of magnesium sulphate in
water, kieserite serves very well ; to the cold filtered solu-
tion add sodium carbonate solution in slight excess, mix
well in the cold, filter and wash slightly ; the filtrate may
be used to prepare glauber-salt ; transfer the precipitate
of magnesium carbonate to a suitable vessel, add water and
boil for 15 minutes; filter and wash on a filtering plate,
suck as dry as possible, remove from filter and dry at
ioo° C.
POROUS CALCIUM CHLORIDE.
CaCl2.
One litre of the solution remaining from the evolution
of carbonic acid from marble and hydrochloric acid (crude)
K. Kippenberger, Zeit. anor. Chem. 6, 177.
88 LABORATORY MANUAL OF
and which no longer reacts with marble is warmed and
then precipitated with milk of lime, made from 35 grams
caustic lime, in an iron pot of 2, litres capacity and filtered.*
After the strongly alkaline solution has been boiled, mix
the filtrate with hydrochloric acid to a strong acid reaction
and evaporate it on the gas stove, with further addition of
acid, in- a porcelain dish of y2 litre capacity. As soon as
a coating of salt begins to form the heat is reduced, a little
fuming hydrochloric acid is added, and the whole left stand-
ing quietly without stirring; the mass becomes entirely dry
in the course of from four to five hours. Now carefully re-
move the calcium chloride from the dish with a knife,
break the large pieces while still hot in a warm mortar,
screen the pieces as quickly as possible in sieves from 1 to 5
mm mesh, and fill immediately into well-stopperd speci-
men bottles.
The caustic lime precipitates from the marble solution
magnesia, as well as the oxides of iron and manganese.
(Very often in standing, basic calcium chloride 3CaO,
CaClfc -f 15H30 separates from the filtrate in long prisms).
In evaporating to dryness the solution must be acidified
with hydrochloric acid and the heating must be a gradual
one, otherwise the calcium chloride will lose HC1. and
take on a strong alkaline reaction.
Porous calcium chloride is a pure white, porous, very
hydroscopic mass, which dissolves clearly in water, and in
alcohol the water solution should show a reaction which is
slightly alkaline.
* In place of this you can also proceed from the residue of ammonia
production, consisting of a mixture of calcium chloride and surplus lime.
Boil the same with water until the last traces of ammonia have passed away,
then filter and continue as stated above.
INORGANIC PREPARATIONS. &9
CALCIUM CHLORIDE.
CaCl2, crysfa/tized +6H20.
Dilute I part of crude hydrochloric acid with 6 parts ot
water, and add thereto marble or chalk until the last por-
tion added remains undissolved ; add now some slacked
lime, then hydrogen sulphide, until a filtered portion of the
mixture is no longer altered by ammonium sulphide.
Then let the mixture stand covered for 12 hours at a
gentle heat, filter, exactly neutralize the filtrate, concen-
trate by evaporation and crystallize.
Solution of pure calcium chloride must be perfectly
neutral, and neither be colored or precipitated by ammo-
nium sulphide ; nor ought it to evolve ammonia when
mixed with potassa or lime.
CALCIUM CARBONATE.
CaCo3.
Solution of pure calcium chloride is heated to boiling
and precipitated by a slight excess of solution of ammo-
nium carbonate with addition of some ammonia. The
precipitate is washed five or six times with hot water by
decantation, then is brought upon a filter and further edul-
corated until the washings give no turbidity with silver
nitrate. The contents of the filter are then dried and
bottled.
Calcium carbonate for use as a flux must be free from
salts of the fixed alkalies. When washed with hot water
the washing must yield no residue when evaporated to
dryness.
9<D LABORATORY MANUAL OF
CRYSTALLINE MONOCALCIUM PHOSPHATE.
CaH4(P04),.
Neither the crystalline nor the honey-like commercial
variety of monocalcium phosphate corresponds with the for-
mula CaH4(P04)2, owing to the free sulphuric acid in
the crude liquor acting on the phosphate during evapora-
tion. By leaving tricalcium phosphate in contact with a
solution of the honey- like commercial variety for some
time, a solution is obtained which, on gentle evaporation,
yields crystals of pure monocalcium phosphate.*
CALCIUM CHROMATE.
CaCr204.
The process is based on the fact that when chromium
oxide (Cr203) is heated with a mixture of calcium chloride
and oxide, a chromite is formed (CaCr204) which absorbs
oxygen from the air and yields calcium chromate. The
finely powdered mineral is mixed with paste composed of
lime, calcium carbonate and a concentrated solution of
calcium chloride, in such proportion that the lime and
the calcium carbonate are slightly in excess, of the amount
necessary to combine with the chromium oxide present,
while the calcium chloride is about one-third of the total
lime used. The mixture, on exposure to air, hardens and
is moulded into bricks, which are dried and subsequently
roasted at a temperature sufficient to convert the calcium
carbonate into lime. The bricks are exposed to the action
of air for about one month, then lixiviated with hot water
to remove the calcium chloride, and the residue containing
* G. Pointet, Bull. Soc. Chim. [3] 5, 254.
INORGANIC PREPARATIONS. 91
the calcium chromate is treated with alkali carbonate or
sulphuric acid in the usual way, according as an alkali
chromate or chromic acid is required.*
ZINC FREE FROM ARSENIC.
Zn.
One kilo commercial zinc is melted in a hessian cru-
cible. Into the red-hot metal plunge pieces of anhydrous
magnesium chloride, forcing them to the bottom of the
crucible, and allow them to remain there until dissolved.
To retain the specifically light chloride below the fused
metal an iron wire is employed, the lower part of which
is twisted into a close spiral. Fasten in the small bell so
constructed, the magnesium chloride by means of a little
flower-wire, and press the wire into the metal. After
adding 1 5 grams of the chloride allow the crucible to cool
sufficiently to prevent the metal from igniting upon open-
ing it, and (the metal should be still liquid) pour it in
the finest possible stream into a pail of water. The gran-
ules upon removal from the water are drained and dried
by heat.
3MgCl2 + 2As = 3Mg + 2AsCl3.
The arsenic chloride and undecomposed magnesium chlo-
ride pass off in thick clouds.
The zinc so obtained contains magnesium and, so dif-
ferently from c. p. zinc, dissolves very readily in diluted
acids. To test it for arsenic, pour over it, in a test tube,
dilute (1.1) hydrochloric acid and cover the tube with a
small filter, the tip of which is moistened with a drop of
J. Massignon and E. Vatsl, Bull. Soc. Chim. [3] 5, 371.
92 LABORATORY MANUAL OF
cone, silver solution (i.i). Yellow silver arsenite Ag3As03
forms after a time, which turns black and decomposes in
water.*
ZINC EISEN.
From one to two pounds of zinc are melted in a clay
crucible, 3 to 3.5 ozs. of anhydrous sodium ferrous chloride
are thrown in, and the crucible is immediately covered ;
violent reaction ensues, and the alloy is produced ; it is
very brittle, has a full metallic lustre, and is easily pul-
verized.!
STRONTIUM HYDROXIDE.
Sr(OH)2 + 8H20.
A well mixed mass of 150 grams finely powdered
celestinef and 50 grams wood charcoal is pressed into a
hessian crucible and covered with a layer of powdered
coal. Close the crucible with an accurately fitting iron
cover, provided with a rim, and heat at white heat for an
hour in the Roessler gas furnace. The cool product should
dissolve in dilute hydrochloric acid with vigorous evolution
of sulphureted hydrogen, leaving only a slight coaly
residue ; test a portion in this manner : Suspend the mass
in a porcelain dish in a litre of hot water, and add to the
solution scales of copper (100 to 150 grams which have been
moistened with a little HN03 and then annealed), until a
filtered sample treated with lead acetate no longer pro-
* L. L'Hote, Compound 98, 1491.
f H. N. Warren, Chem. News, 55, 100.
\ Strontium sulphate.
INORGANIC PREPARATIONS. 93
duces a brownish-black precipitate. Then filter hot into a
beaker, boil the residue with IOO c. c. water, cover the
entire filtrate, and allow it to crystallize. After the lapse
of 24 hours the liquid is poured off from the crystals,
which are very quickly dried on an earthen plate and
placed in a closed and paraffined vessel. The solution is
rapidly evaporated to 300 c. c. in an iron dish, to obtain a
second crop of crystals.
The strontium sulphate, by ignition with charcoal and
exclusion of air, is transformed into strontium sulphide,
which by the action of copper oxide is converted into stron-
tium hydroxide: SrSo4 + 4C = SrS + 4CO ; SrS + CuO +
HgO = Sr(OH2) 4- CuS.
Strontium hydroxide crystallizes in perfectly clear,
easily efflorescent square tablets or needles of strong
alkaline taste, dissolving readily and without residue in
hot water. It melts easily on warming, and on further
heating solidifies again to a white mass with loss of its eight
molecules of water of crystallization; at higher tempera-
tures it melts once more, and finally passes into strontium
oxide. An acetic acid solution should not be precipitated
by potassium dichromate (Barium), but should, on the
other hand, be precipitated so completely by H3S04 that
ammonium oxalate does not form a precipitate in the
filtrate (absence of lime).
PREPARATION OF PURE STRONTIUM SALTS.
The following process is given for obtaining a pure
strontium salt from a barytostrontianite containing iron,
aluminium, magnesium, calcium and barium as impurities:
94 LABORATORY MANUAL OF
The mineral or the sulphide resulting from the reduction
of the sulphate is dissolved in such a quantity of hydro-
chloric acid (20 per cent.) as to leave a little undissolved.
The aluminum and iron are precipitated by ammonia, fil-
tered ofT, and excess of sulphuric acid added. The pre-
cipitate is washed first with dilute sulphuric acid (1 to 2 per
cent.) and finally with water; it is thus freed from magne-
sium and calcium. It is now digested in the cold for
some days with ammonium or potassium carbonate solu-
tion (1.0 per cent.), washed well, the residue treated with
dilute hydrochloric acid, and the solution decanted ;
after remaining for 24 hours this is filtered, and 200 grams
of hydrochloric acid (sp. gr. 1 . 1 7) per litre are added
to it, together with 2 or 3 grams of precipitated strontium
sulphate, which may contain barium. After some hours
the solution is filtered, evaporated to dryness, dissolved in
water, filtered and crystallized. The spectrum given by
the salt thus obtained shows strontium to be the only metal
present.*
CADMIUM CARBONATE.
CdC03.
IOO grams of cut or granulated commercial cadmium
are placed in a flask with 400 c. c. cold nitric acid of 1.20
sp. gr. Run the nitrogen dioxide evolved into the drain;
after the action has completely ceased, puur the liquid
from the undissolved residue into a porcelain dish of 6
litres capacity ; dilute with 4 litres hot water and add a
little powdered commercial ammonium carbonate, until a
* By Barthe and Falieres, Bull. soc. Chin. [3], 7, 104-108.
INORGANIC PREPARATIONS. 95
permanent precipitate is formed ; filter and precipitate the
cadmium in the filtrate with about 150 grams ammonium
carbonate ; decant several times with hot water in tall glass
cylinders, and preserve the carbonate as paste, or else dry-
on the water-bath.
3Cd + 8HNO3 =3Cd(N03)2 + 2NO 4 4H20.
The foreign metals, with the exception of zinc and iron, do
not remain in solution, but are again precipitated in me-
tallic form by the surplus cadmium. The iron precipitates
with the first portion of cadmium carbonate :
3CdC034 Fe2(N03)64- 3H20 = 3Cd(N03)3 -f Fe2(OH)6 +
3COg.
The zinc is retained in solution by the surplus ammonium
salt.
The pure white salt passing into brown cadmium oxide
on igniting, and easily dissolving in diluted acids with effer-
vescence, is to be tested particularly for antimony, bismuth,
copper, lead, iron and zinc according to the usual method
of analysis.
BARIUM OXIDE.
BaO.
150 grams o{ heavy spar* are reduced with 40 grams
wood charcoal, in the same manner as described for celes-
tine (on page 92), and the barium sulphide obtained is de-
composed in a litre flask, with dropping funnel and gas
conduit tube, by means of dilute HNO3, filtered and
evaporated to crystallization. Of this, or else of commer-
cial barium nitrate, 1 j4 kilos are gradually placed with an
* Barium sulphate.
96 LABORATORY MANUAL OF
iron spoon in a red-hot Hessian crucible, which is kept cov-
ered with an earthen cover. After having added the whole
quantity the closed crucible is heated for another hour at
very high temperature. After the crucible has again partly
cooled, remove the upper layer of the barium manganate,
the green-colored layer of the crucible, and fill the barium
oxide into small flasks, at once sealing them hermetically.
The barium nitrate at first passes into barium nitrite
and then further into barium oxide, at white heat :
Ba(N03)3 = Ba(N03)3 + 20.
Ba(NOg)2 = BaO -f 2N + 3 0.
Barium oxide comes in grayish-white porous pieces,
which evolve heat with water and dissolve completely in
dilute hydrochloric acid without effervescing; this solution
should not discolor permanganate nor blue potassium iodide
starch paper (barium nitrate and barium superoxide).
BARIUM CHLORIDE.
BaCl3 + 2H30.
a. From heavy spar. Mix together 8 parts of pul-
verized barium sulphate, 2 parts of charcoal powder, and I
part of common rosin. Put the mixture in a crucible and
expose it in a blast furnace to a long-continued red heat.
Triturate the crude barium sulphide obtained, boil about tg
of the powder with 4 times its quantity of water, and add
hydrochloric acid until all effervescence of hydrogen sul-
phide has ceased, and the fluid manifests a slight acid reac-
tion. Add now the remaining to part of the barium sul-
phide, boil some time longer, then filter, and let the alkaline
INORGANIC PREPARATIONS. 97
fluid crystallize. Drain the crystals, redissolve them in
water, and crystallize again.
b. From witherite. Pour 10 parts of water upon I
part of pulverized witherite, and gradually add crude hy-
drochloric acid until the witherite is almost completely dis-
solved. Add now a little more finely pulverized witherite,
and heat, with frequent stirring, until the fluid has entirely
or very nearly lost its acid reaction ; add solution of barium
sulphide as long as a precipitate forms ; then filter, evap-
orate the filtrate to crystallization, and purify by crystal-
lizing again. For use, dissolve I part of the barium chlo-
ride in 10 parts of water.
Pure barium chloride must not alter vegetable colors ;
its solution must not be colored or precipated by hydrogen
sulphide, nor by ammonium sulphide. Pure sulphuric
acid must precipitate every fixed particle from it, so that
the fluid filtered from the precipitate formed upon the ad-
dition of that reagent leaves not the slightest residue when
evaporated on platinum foil.
BARIUM NITRATE.
Ba(N03)2.
Treat barium carbonate, no matter whether witherite
or that precipitated by sodium carbonate from solution of
barium sulphide, with dilute nitric acid free from chlorides,
and proceed exactly as directed in the preparation of
barium chloride from witherite.
Solutions of barium nitrate must not be made turbid by
silver nitrate solutions. The other tests are the same as
for barium chloride.
98 LABORATORY MANUAL OF
BARIUM PEROXIDE.
Ba02.
BARIUM PERHYDRATE.
Ba(OH)4 + 6H20.
A combustion tube is filled with 30 grams powdered ba-
rium oxide, moderately heated in a combustion furnace, and a
rapid current of oxygen dried with cone, sulphuric acid
conducted over it. The solid peroxide, after being ground
with a little water, is placed in 50 c. c. dil. hydrochloric acid
which has been cooled to o° C, then the still faintly acid
solution is filtered and allowed to flow into 500 c. c. baryta
water which has been cooled to o° C, and saturated cold.
The separated precipitate, consisting of glistening crystalline
scales, is sucked dry, washed with a little ice-water, and
preserved as paste.
With moderate heat the barium oxide adds another
atom of oxygen. The barium peroxide decomposes with
hydrochloric acid: 2Ba03 f 4HC1 = 2BaCl2 + 2H202; the
hydrogen peroxide with baryta: H203 + Ba(OH)3 =
Ba(OH)4.
The barium superoxide must not inflame by grinding
with water (property of barium oxide). The value of the
perhydrate is proven, if hydrogen peroxide is produced
from the preparation.
BARIUM CARBONATE.
BaC03.
Dissolve crystallized barium chloride in water, heat to
boiling, and add a solution of ammonium carbonate mixed
INORGANIC PREPARATIONS. 99
with some ammonia, or of pure sodium carbonate, as long
as a precipitate forms ; let the precipitate subside, decant five
or six times, transfer the precipitate to a filter, and wash
until the wash water is no longer made turbid by silver
nitrate solution.
Pure sulphuric acid must precipitate every fixed particle
from a solution of barium carbonate in hydrochloric acid.
BARIU M DITHIONATE.
BaS206 + 2H20.
DITH IONIC ACID.
H2S206 4- X H,0.
ioo grams finely powered black oxide manganese is elu-
triated by mixing with water in a large mortar, decanted,
and the remaining coarse powder again mixed with water ;
this is repeated until the entire mineral is suspended in
water, then allow it to settle in tall cylinders ; the water is
removed by means of a syphon, and the black oxide of man-
ganese brought into a liter flask with y2 litre water. A
current of sulphur dioxide is passed through the mixture,
the flask being cooled with ice. When the bulk of the
black oxide manganese has dissolved add to the solution
which has been heated in a dish cone, barium hydrate
solation until a filtered sample fails to yield a flesh-colored
precipitate with ammonium sulphide. The precipitate is
then filtered, boiled with hot water, and the combined fil-
trates treated hot with carbonic acid until neutral. The
barium dithionate crystallizes from the filtrate on concen-
tion.
Dithionic Acid. — 59 grams barium dithionate are dis-
L»tC.
IOO LABORATORY MANUAL OF
solved in water ; 20 grams of a solution of sulphuric acid
diluted with water are added to the solution until it will no
longer react either with sulphuric acid or with barium chlo-
ride. After filtering off the barium sulphate the dithionic
acid is concentrated on a flat porcelain plate in vacuum
over sulphuric acid to a sp. gr. of 1. 347.
The peroxide withdraws from 2 molecules of sulphur-
CA TT
ous acid two atoms of hydrogen ; 2HS03H — 2H = oq3 jj
The manganese salt of the dithionic acid is decomposed
by the excess of baryta water.
Mn&Oe + Ba(OH)2 == BaS306 + Mn(OH)2.
Barium dithionate forms colorless, glossy crystals,
which in a powdered condition lose their water of crystal-
lization (10.81 %) at ioo° C.
Determine the percentage of barium oxide (45.96 %
BaO) by igniting the purified salt and then weighing the
residue of barium sulphate.
DISTILLED MERCURY.
Hg.
In a combustion furnace, one end of which is lifted
15 mm. above the other, lay a tube of hard Bohemian
glass, both ends of which are bent downward, as shown in
figure 8.
The end drawn out is connected by means of a heavy
walled, closely fitting rubber tube with a glass tube of
medium thickness about 10 mm. outside diameter, and
of such a length that the entire vertical tube up to the
lower opening which turns upward is about 700 mm. The
INORGANIC PREPARATIONS.
IOI
giass tube stands in a narrow glass cylinder. The other
end of the combustion tube is bent upward somewhat
within the furnace so that the last flame of the furnace
stands below the highest point * of the bend of the tube.
Fig, 8.
From there the tube leads downward 20 cm. without re-
duction in size ; into the end of this tube by means of a
rubber tubing,t a second glass tube is inserted, bent hook-
form at the bottom, which extends at least 5 cm. into the
wider tube, and is about 80 cm. in length. To set the
* At the point of the tube, place a loose plug of asbestos.
f In order to have at this point a perfectly airtight connection, add the
contrivance pictured in the small illustration on the right, which is intellig-
ible without further explanation. The small space ^surrounding the shaded
part) formed by a rubber stopper and a small pieces of wide glass tubing is
filled with mercury.
102 LABORATORY MANUAL OF
apparatus in motion pour into the cylinder commercial
mercury or else mercury which has become impure by use
with other metals, and exhaust the apparatus with a filter
pump, adding an empty Woulff bottle. As soon as the
mercury has risen so high that it runs along in a thin
stream from one end of the combustion furnace to the
other, the rubber tubing leading to the pump is closed se-
curely with a pinch-cock. Now the furnace is heated with
a low flame while the mercury boils gently and distills
through the asbestos plug. As soon as the tube leading
downward is filled half way with mercury, open the pinch-
cock and carefully allow air to enter the exhausted tube ;
the mercury column now prevents air from entering this
side of the apparatus. The apparatus works automatically,
and the distilling mercury flows continually into a vessel
placed below ; from time to time the quantity of mercury
in the cylinder is replaced.
The mercury should be 1 3- 595 sp- gr. at o° C. and
possess a pure silver gloss, fuse easily, and in pouring out,
form round regular drops leaving no threadlike residue.
5 grams heated in a porcelain crucible should not leave a
weighable and fusible residue.
PURIFICATION OF MERCURY.
Mercury can be completely freed from lead, zinc, tin,
and other impurities by placing it in a slightly inclined
glass tube provided with a funnel at the lower extremity,
and aspirating a gentle stream of air through the apparatus
for about 48 hours. The oxides of the metals collect at
the upper end of the tube, and after about 24 hours, as a
INORGANIC PREPARATIONS. IO3
rule, the surface of the mercury is quite clean and the
operation is finished. Large quantities can be treated in
this way, but mercury which has been used for amalgamat-
ing zinc contains such a large amount of impurity that this
method cannot be used. Silver is not removed by this
process.
Mercury is usually purified by shaking in a topped
separator with cone, sulphuric acid, allowing time to
settle and drawing off, continue until the mercury is bright
and no longer imparts a color to the mercury.*
MERCURIC CHLORIDE.
HgCl2- (FROM RESIDUES.)
The residues, oxydized with crude hydrochloric and
nitric acids and then dried on the water bath are subjected
to slow sublimation in a porcelain dish on a sand-bath with
a large funnel set over it. Of the sublimate thus obtained
dissolve according to its purity 1-10 to 1-5 in hot water,
precipitate with soda lye, and grind the so obtained mer-
curic oxide after washing and drying with the main quan-
tity of the sublimate The acquired powder which turns
black through the formation of mercuric oxychloride, is
placed into a flask, covered loosely with a watch glass and
heated on the sand bath over a small flame. The subli-
mate gathers at the upper part of the flask in fine long
crystals. After final sublimation remove the flask from
the bath, break off the bottom by quickly passing over it
a damp sponge and separate the crystals from the glass on
a large sheet of paper with the aid of a goose quill. In
J. M. Crafts, Bull. Soc. Chim. 49, 856.
104 LABORATORY MANUAL OF
case there are poor crystals among them, they are to be
recrystallized in four parts of boiling water.
The crude sublimate is contaminated by other unstable
metallic chlorides, but these are all decomposed by mer-
curic oxide ; for instance : Fe3Cl,--f 3HgO = Fe203-f 3HgCl2.
Pure white, rhombic prisms of mercuric chloride dis-
solve readily without residue (calomel, iron oxide, etc.) in
cold alcohol, ether and hot water ; heated in a test tube
volatilize without residue.
MERCURIC CYANIDE.
Hg(CN)2.
A diluted prussic acid solution is mixed in a flask with
yellow mercuric oxide until the solution reacts strongly
alkaline to litmus paper. Filter and add to the filtrate
enough prussic acid to make the odor of it noticeable and
so that the filtrate will react distinctly acid, then evaporate
to crystallization. Before the mother liquor is again evap-
orated to crystallization, add a little more prussic acid.
Mercuric cyanide crystallizes in square columns and
pyramids soluble in 1 1 parts of cold water and have a
neutral reaction. Heated in small tubes, the salt develops
cyanogen, gives a destillate of mercury drops and leaves
black paracyanogen.
CINNABAR.
HgS.
60 grams mercury are intimately mixed in a mortar
with 23 grams flowers of sulphur until the mercury has
INORGANIC PREPARATIONS. 105
entirely disappeared. Pour over this a solution of 15
grams caustic potash in 80 c. c. water and digest several
days at about 45° C, stirring frequently and replacing the
evaporated water. After the mass has become of a nice
red color, it is separated from the unaltered mercury and
the largest part of the sulphur by elutriation, boiled with a
solution of sodium sulphite, and washed with hot water.
Cinnabar is a scarlet-red powder and when heated
strongly in small tubes volatilizes without residue.
MERCUROUS NITRATE
Hg2(N03)2 crystallized -f 2H20.
Pour 1 part of pure nitric acid of 1.2 sp. gr. on 1
part of pure mercury in a porcelain dish, and let the vessel
stand twenty-four hours in a cool place ; separate the
crystals formed from the undissolved mercury and the
mother liquor, and dissolve them in water mixed with one-
sixteenth part of nitric acid, by trituration in a mortar.
Filter the solution, and keep the filtrate in a bottle with
some metallic mercury covering the bottom of the vessel.
The solution of mercurous nitrate must give with di-
lute hydrochloric acid a copious white precipitate of mer-
curous chloride ; hydrogen sulphide must produce no pre-
cipitate in the fluid filtered from this, or at all events, only
a trifling black precipitate (mercuric sulphide).
106 LABORATORY MANUAL OF
MERCUROUS IODIDE.
Hg2I3
If a saturated solution of mercurous nitrate as free as
possible from oxide and slightly acidified with nitric acid,
is heated to boiling with iodine, the latter becomes covered
with a yellow powder, which partially dissolves, and the
solution, after decantation into a warm dish, deposits in the
dark, lustrous yellow, transparent, tetragonal scales of
mercurous iodide ; these must be dried in the dark at or-
dinary temperature. When the mercurous nitrate solution
is treated with an alcoholic solution of iodine in the cold,
small, yellow spangles of mercurous iodide are obtained,
but the product formed by the old methods of preparation,
by rubbing together molecular proportions of mercury and
iodine, and adding potassium iodide in solution to a solu-
tion of mercurous salt, have a green color, and are impure,
although the pure yellow compound can be obtained by
reversing the last process, and adding an excess of a dilute
solution of mercurous nitrate to potassium iodide in solu-
tion. The crystallized compound shows the usual color
change, yellow at ioo° C. passing through orange to gar-
net-red at higher temperatures. Sublimation commences
at 1 10 to 120° C. and the salt fuses at 2900 C. without de-
composition. Towards acids and solvents, the crystallized
compound behaves like that precipitated by potassium
iodide ; ammonia and caustic alkalies render it green, and
on heating convert it into the corresponding alkaline iodide
and metallic mercury. The crystallized iodide is less
sensitive to light than the precipitated yellow compound,
which rapidly becomes black even in diffused daylight.*
* A. Stroman, Ber. 20, 2818.
INORGANIC PREPARATIONS. 107
MERCUROUS BROMIDE.
Hg2Br3.
When mercurous nitrate solution is treated with bro-
mine under similar conditions, small, white( nacreous,
tetragonal scales of mercurous bromide are obtained, and
the same compound separates in yellow, crystalline span-
gles when an alcoholic or aqueous solution of bromine is
used. It sublimes at 171 ° to 1760 C. in small scales, is less
sensitive to light than the iodide, dissolves in hot sulphuric
acid with the evolution of sulphurous anhydride becomes
black and gradually decomposes when heated with dilute
and concentrated hydrochloric acid, dissolves slowly in hot
nitric acid (sp. gr. 1.42), and decomposes with the forma-
tion of the corresponding bromides when treated with am-
monia and caustic alkalies.
BORON.
B2.
100 grams fused hot finely powdered borax are well
mixed with 50 grams magnesium powder, the mass poured
in a Hessian crucible, pressed down well and covered with
a layer of pure borax. All these operations must be done
rapidly and are to be carried on in warmed vessels, as the
anhydrous borax is very hygroscopic. The crucible is
closed with a specially well-fitting cover of strong sheet-iron
with a rim, and heated in a Roessler's furnace for half an
hour up to red heat. After cooling, grind the product,
boil it with water, then with hydrochloric acid and finally
108 LABORATORY MANUAL OF
again with water and dry the grayish-brown powder on
the water-bath.*
PREPARATION OF AMORPHOUS BORON.
Another method is to pass a current of 35 amperes
through boric anhydride mixed with 20 per cent, of sodium
borate and heated at 12000, boron is liberated, but im-
mediately recombines with oxygen with vivid incan-
descence.
It is well known that when boric anhydride is heated
with the theoretical quantity or an excess of magnesium,
reduction takes place with formation of magnesium borides.
If the boric anhydride is in considerable excess different
results are obtained. There are two magnesium borides,
one unstable and decomposed by water with liberation of
hydrogen and boron hydride, the other stable and not af-
fected by water, hydrochloric acid, or nitric acid.
70 grams of finely powdered magnesium free from iron
and silicon, are intimately mixed with 210 grams of re-
cently fused boric anhydride. The mixture is heated to
bright redness in a clay crucible, and in a few minutes an
energetic reaction takes place. The central part of the
product is boiled with water and hydrochloric acid until
the magnesium borate is removed, then treated for a long
time with successive quantities of pure boiling hydro-
chloric acid, washed with water, treated with alcoholic
potash, again washed with water, boiled for several hours
with hydrofluoric acid, washed with water, and dried in a
vacuum. The product is a very light maroon powder
which does not alter when exposed to air ; it contains 94 to
Gattermann, Ber. 22, 195.
INORGANIC PREPARATIONS. IO9
95 per cent, of boron, 2.3 to 3.75 per cent, of magnesium
and 1.2 to 1.6 per cent, of insoluble matter.
If this product is fused with 50 times its weight of boric
anhydride, and the product treated in the same way as the
original product, a maroon powder is obtained containing
only traces of magnesium.
One product contained boron, 98.30 ; magnesium, O.37;
insoluble, 1.18 = 99.85.
If the boron is required perfectly free from nitride, re-
duction must be affected in a crucible brasqued with a mix-
ture of finely powdered titanic oxide and carbon ; the
product contains from 92.6 to 99.2 per cent, of boron.
Boric anhydride may also be reduced by magnesium in
porcelain dishes in an atmosphere of hydrogen, and a very
pure product obtained, but the yield is small.*
It can also be prepared by mixing 3.5 grams of boric
anhydride and 1 1 grams of calcium fluoride by gently
heating with cone, sulphuric acid ; the boron fluoride
evolved is passed over heated potassium contained in a
series of bulbs. Potassium fluoride and boron are formed
and easily separated by washing with water. Amorphous
silicon may be prepared in a similar manner.t
BORAX.
Na2B407.
An intimate mixture of well-ground common salt and
boric acid is introduced into an acid-proof, tubulated clay
retort, and heated to slightly above a low red heat, when
sufficient superheated steam is admitted through the tu-
* By H. Moissan, Compt. rend., 114, 392—397.
f S. G. Rawson, Chem. News, 58, 283.
IIO LABORATORY MANUAL OF
bulature to condense the hydrochloric acid, which is evolved,
the acid being collected in a cooled receptacle attached to
the retort neck. Ultimately anhydrous borax only is left
in the retort, and this is thrown, while still hot, into cold
water and crystallized.*
BORACIC ACID.
H3BO3.
200 grams powdered borax are dissolved in one-half
litre of boiling water, and 300 c. c. dil. hydrochloric acid
added. After expiration of a day suck the separated scaly
crystals dry on the platinum cone, wash them with a very
little water, and recrystallize once from water.
The white, pearl-like crystals must dissolve in 6 parts
alcohol and 25 parts cold water and on heating, after
evaporation of the water, melt to a colorless glass which
when cooled remains transparent. The watery solution
reddens litmus paper ; if turmeric paper strips are saturated
with it and dried in a warm place, the yellow color will be
changed to an orange-brown, which with alkaloids be-
comes greenish-black. The impurities usually present are
hydrochloric and sulphuric acids.
SILI CON.
Si
Amorphous silicon is readily obtained by the action of
magnesium on silica, provided that the materials are quite
dry, and that the action is moderated by the presence of
magnesium oxide. In absence of the oxide, the tempera-
* By H M. Warren, Chem. News, 67, 244-245
INORGANIC PREPARATIONS. Ill
ture of the reaction is too high, and some of the silicon is
fused. Silica is not so satisfactory as magnesia for this
purpose. Powdered quartz and magnesium powder such
as is used for photographic purposes are mixed in the cal-
culated proportions, and to the mixture is added one-fourth
of its weight of calcined magnesia. The three substances
are very intimately mixed and placed in a fire clay cruci-
ble, which they must not more than half fill. A layer of
magnesia is placed on the top, and the crucible is then
heated at 149 to 205 ° C. in order to thoroughly dry the con-
tents. The crucible with its cover is then heated to red-
ness for a few minutes, and as soon as the action ceases it
is allowed to cool. Reduction takes place at 2820 C. If
the mixture is placed on a plate and covered with mag-
nesium powder, and the latter is ignited, reduction spreads
throughout the mass.
The product is heated with hydrochloric acid, then
with boiling sulphuric acid, then two or three times alter-
nately with hydrofluoric acid and sulphuric acid, and,
finally, with hydrochloric acid. After drying, the silicon
forms a maroon colored, homogeneous powder, containing
only 1.0 to 0.4 per cent, of impurities. Any small globules
of fused silicon can, if necessary, be removed by levigation.*
Another method is to heat 40 grams of finely pow-
dered sand with 10 grams of magnesium in not too
thin a test tube, the whole tube is heated first mod-
erately, and then a small portion is heated strongly,
beginning at the lower end and continuing up-
wards. The product is grayish-black. The frag-
ments of the tube, after the substance has been taken out,
By Vigouron, Compt. rend., 1895, 120, 94.
112 LABORATORY MANUAL OF
should be treated with acid, as the adherent substance will
decompose in moist air and evolve silicon hydride. Silicon
is obtained by heating the substance in a closed crucible
with zinc ; on dissolving out the zinc, it is obtained in steel-
blue needles.*
It can also be prepared by introducing aluminium,
in pieces the size of a walnut, into a clay crucible
containing a fused mixture of 4 parts of potassium
silico-fluoride, 1 part of potassium chloride, and 2
parts of potassium carbonate, and when the violent
reaction has subsided, the mass is heated to whiteness for
five minutes. When cool, the crucible is smashed ; the
button, carefully detached from adhering slag, is placed in
a plumbago crucible with 12 parts by weight of aluminium
and 2 of tin, and covered with a layer of sodium silicate,
the mixture is submitted for two hours to the strongest
heat obtainable. When cold, the piece of aluminium is
broken, when the new modification of silicon is found in
large, lustrous, infusible, oblique octahedra, insoluble in all
acids except hydrofluoric. f
Still another method is as follows : Small bars of
" silicon-eisen " are suspended in dilute sulphuric acid
from the positive pole of a battery of two ferric
chloride cells and are in contact with a platinum
plate forming the negative pole. The iron dissolves and
leaves a residue of graphite, silica, and amorphous silicon,
which is heated to redness in a stream of carbonic an-
hydride, and then to a full red heat in a closed iron
tube with some zinc ; the zinc button obtained in this
*L. Gattermann, Ber. 22, 186.
f By H. N. Warren, Chem. News, 67, 136-137.
INORGANIC PREPARATIONS. 113
manner is dissolved in hydrochloric acid, when crystal-
line silicon remains insoluble ; by heating the amor-
phous silicon at a full white heat with aluminium instead
of zinc, graphitoidal silicon is obtained. When an alloy
of aluminium and silver is heated to an intense white
heat with potassium silicofluoride, small quantities of
silicon are produced in the form of a bright reddish-
brown powder.*
CRYSTALLINE SILICIC ACID.
H3Si03.
Silicious limestone is treated with crude concentrated
hydrochloric acid until carbonic anhydride ceases to be
evolved, filter and add to the filtrate 29 to 31 per cent,
hydrochloric acid until a cloudiness appears. After re-
maining 24 hours the solution is decanted, the precipi-
tate strained and washed, finally with distilled water and
then dried on porcelain. Silicic acid so obtained is
crystalline and corresponds to the formula H2Si03 +3H2O
or H2Si03 + 2H20. It is more soluble than the amor-
phous variety.!
SILICON CHLORIDE.
SiCl4.
Take a hard glass tube 2 m.m. wide, fill it half way
with the crude amorphous silicium as described above,
lay it horizontally in a combustion furnace and at mod-
erate heat, lead a current of dry chlorine over it.
* H. N. Warren, Chem. News, 57, 54.
f H. Hager, Pharrh. Centralb. 29, 115.
114 LABORATORY MANUAL OF
The distilling silicon chloride is condensed in a receiver
which is surrounded by a freezing mixture of ice and com-
mon salt, while the surplus chlorine is absorbed in soda
lye. The greenish product is shaken with a little mercury,
and then distilled from the water- oath with a thermome-
ter and condenser attached.
Si 4. 4CI = SiCl4. The free chlorine dissolved in the
silicon chloride is removed by shaking with mercury.
The silicon chloride should boil at 58 to 6o° C. and
appear as a colorless, mobile liquid fuming strongly when
exposed to the air, it is decomposed by water with separa-
tion of hydrated silicic acid :
SiCl4 + 4H30 = Si(OH)4 + 4HC1.
CHLORIDES OF SILICON, ALUMINIUM, ETC.
Iron alloys of silicon or aluminium are heated to red-
ness in a clay crucible, and a current of chlorine gas is
passed into the mass, suitable means being adopted to col-
lect the volatile products. With chlorine and silicon-iron,
the ferric chloride is condensed first, then the silicon
chloride ; if hydrogen chloride is used instead of chlorine,
the ferrous chloride formed remains in the crucible and
silicon chloroform distills off. The aluminium chloride ob-
tained from aluminium iron is purified by mixing with iron
borings and distilling, or if the aluminium iron alloy is
mixed with common salt previous to submitting it to the*
action of chlorine, a sublimate of aluminium sodium
chloride is obtained.
* By H. N. Warren, Chem. News, 60, 158.
INORGANIC PREPARATIONS. 1 1 5
PREPARATION OF SILICON AND ALUMINIUM
CHLORIDE.
Silicon chloride, mixed with but little ferric chloride
and readily purified by redistillation, is obtained by pass-
ing chlorine into siliconeisen, containing 15 per cent, of
silicon, heated to redness in a tubulated clay retort, and
retaining the less volatile ferric chloride in the upper
part of a suitable adapter, while the lower part is cooled
in a freezing mixture to condense the silicon chloride. By
using hydrochloric acid gas instead of chlorine, ferrous
chloride, and the more volatile silicon-chloroform, SiHCl3,
are obtained.
By the action of chlorine on an alloy of iron with 10
per cent, of aluminium, aluminium chloride is produced,
which can be purified by distillations from iron borings.
When the pulverized alloy is previously mixed with sodium
chloride, the passage of chlorine gives rise to the sublima-
tion of aluminium sodium chloride.
ALUMINIUM HYDRATE,
Al3( O H )e, from Cryolite.
50 grams cryolite are finely powdered, then thoroughly
mixed with 50 grams calcined marble and ignited for half an
hour in a platinum crucible placed in Roessler's furnace.
The powdered melt is boiled with water, possible traces of
calcium removed from the filtered solution by a few drops
of soda solution and then precipitated hot with carbonic
H. N. Warren, Chem. News, 66, 113-114.
Il6 LABORATORY MANUAL OF
acid. The separated aluminium hydrate is washed by de-
cantation with a good deal of hot water, collected, dried
on the water bath, and if desired, transformed into an-
hydrous aluminium sesquioxide by ignition. The filtrate
when evaporated, leaves pure sodium carbonate.
The aluminum sodium fluoride is decomposed by
caustic lime, forming sodium aluminate soluble in water:
NadAl3Fio + 6CaO = Na6Al206 + 6CaF2.
The sodium aluminate is decomposed by carbonic acid :
2Na6Al206 + 6H2C03 = 2A12(0H)„ + 6Na2C03.
REDUCTION OF ALUMINIUM OXIDE.
A1203.
Two parts of pure, finely powdered aluminium oxide
is made into a paste with one part of petroleum or some
other hydro-carbon, and then mixed with one part of sul-
phuric acid. When the mass is homogeneous with a pale
yellow tint, and begins to give off sulphurous anhydride, it
is wrapped in paper and thrown into a crucible heated to
above 8oo° C. in order to decompose the hydrocarbon. The
compact product thus obtained is powdered and mixed
with its own weight of a finely divided metal, the mix-
ture being then heated to a white heat in a plumbago
crucible. The regulus after being allowed to cool is found
to contain grains of an aluminium alloy in the midst of a
metallic powder. This method of reduction is applicable
to silica, calcium oxide, magnesium oxide, etc.*
* G. A. Faurie, Compt. Rend. 105, 494.
INORGANIC PREPARATIONS. II 7
ANHYDROUS ALUMINIUM CHLORIDE.
AloCl6.
Dry hydrogen chloride extracts the whole of the alum-
inium from an alloy of copper and aluminium without at-
tacking the copper. The reaction is most energetic a
little below a red heat. The alloys containing 15 to 40
per cent, of aluminium are best powdered, mixed with
powdered charcoal (to prevent the fusion of the remaining
copper), put into a graphite retort, and when heated just
below a red heat a current of hydrogen chloride is passed
through. The aluminium chloride distills over, and may
be condensed in suitable vessels, the liberated hydrogen
passing on.
FORMATION OF ULTRAMARINE IN THE
WET WAY.
The material used is washed kaolin, with the fol-
lowing percentage composition: Silica, 46.83; alumina,
40.25; water, 12.60; potash, 0.37; lime, trace; total,
100.05 ; and was expressed by the formula:
2Si03: 1.997 A1303 :: 1.79 H30.
The ultramarine mixture is made in the proportion —
Washed kaolin, 100 parts ; anhydrous sodium carbonate,
100 parts; sulphur, 60 parts. The mixture is heated in
small porcelain crucibles, holding 15 to 20 grams of the
mixture; this is pressed in, and the top covered to a
By C. F. Mabery, Ber. 22, 2658.
I I S LABORATORY MANUAL OF
depth of 5 to 6 mm. with powdered charcoal, and the cruci-
ble then heated with the lid on. The mixture, after heat-
ing and separation from the charcoal, gives on digestion
with solution of liver of sulphur, the deep blue of ultra-
marine. Kaolin, digested alone with liver of sulphur solu-
tion, is unchanged.*
HYDROGEN BROMIDE.
HBr.
ioo grams benzole and a few grams of anhydrous fer-
rous bromide are placed in a dry two-necked bottle and
135 c. c. bromine allowed to drop in from a dropping fun-
nel with long fine stem. The Woulff bottle is placed in
cold water during the first half of the operation, in order
to control the vigorous heating and volatilization of the
benzole which takes place. The gas is passed through a
small tube charged with anhydrous ferrou bromidef then
through one charged with anthracene and now forms pure
hydrogen bromide. For the production of cone, aqueous
hydrobromic acid, the gas is led into a small bottle, by de-
grees small quantities of water are added with a wash-bot-
tle and cooled with a freezing mixture of ice and common
salt. The saturated solution is preserved in a well stoppered
bottle with cap and kept in a dark place.
C6H6 +4Br = C6H4Br2 + 2HBr.
The small quantity of ferrous bromide (FeBr2) acts as
* By F. Knapp, J. pr. Chem. [2] 32, 375-39Q-
f Produced by mixing 25 grams ferrous FeBr2 bromide with 3 c. c. bro-
mine in the cold.
INORGANIC PREPARATIONS. 119
the transferrer of bromine. The hydrogen bromide, devel-
oped in a very regular stream, carries off benzole-vapors
which bromate in the ferrous bromide tube and are held
back. The gas is freed by the anthracene from the slight
traces of free bromine.
The aqueous solution should be entirely colorless, fume
strongly when exposed to the air, and have a sp. gr. of at
least 1.78 (at oQ C. saturated acid).
Another method : — A mixture of 1 part of red phos-
phorus, 2 parts of water, and sufficient sand to form a
paste, is introduced into a flask, 10 parts of bromine then
gradually added by means of a funnel provided with
a stopcock, the flask gradually warmed, and the mixture
of hydrogen bromide and bromine vapor passed through a
deep glass jar filled with a mixture of red phosphorus and
asbestos, impregnated with concentrated hydrobromic acid.
Every trace of bromine vapor is thus effectually retained,
and the process is continuous and requires no supervision
beyond an occasional shaking of the flask.*
By means of the following arrangement, a large quan-
tity of bromine can be rapidly converted into hydrobromic
acid : A glass tube, 7 inches long and 5/% inch in diameter,
is fitted at each end with a cork carrying a piece of small
tubing and a piece of stout wire. The ends of these pieces
of stout wire, within the longer tube, are joined by a spiral
of platinum wire 1 inch long, and after expelling the air
the spiral is heated to bright redness by an electric current ;
a stream of hydrogen, impregnated with bromine by bub-
bling through that liquid, which maybe heated at 60 ° C, is
passed through the longer tube, and, as long as a slight
*M. Fileti and F. Crosa, Gazetta, 21.
120 LABORATORY MANUAL OF
excess of hydrogen is maintained, hydrobomic acid quite
free from bromine issues from the other end, and is col-
lected in water. There is very little danger from explo-
sion, but to render it impossible, the small supply tube may
be plugged with a little glass wool.*
A convenient method of preparing hydrogen bromide
in quantity is to drop strong sulphuric acid from a tap
funnel on solid potassium bromide heated in a stoppered,
tubulated retort on the water-bath. The gas given off is
contaminated with small quantities of sulphurous anhy-
dride and bromine, from which it is freed by two sets of
wash-bottles, the first of which contains a strong solution
of bromine in hydrobromic acid, the second, amorphous
phosphorus suspended in hydrobromic acid. When all
the sulphuric acid has been added, and the evolution of
gas has slackened, the retort may be heated over a flame.
Another method is to pass sulphurous anhydride
through a solution of bromine (i vol.) in concentrated
hydrobromic acid (i vol.). The evolved hydrogen bro-
mide is then purified as above. t
Hydrogen bromide may also be prepared by adding
bromine (385 grams) to a mixture of liquid paraffin (500
grams) and dry phosphorus in small pieces 50 grams ;
water (about 100 grams) is then gradually run in and the
evolved gas purified by passage over moist phosphorus.f
This method, proposed for the preparation of hydro-
bromic acid, is based on the fact that the action of
gaseous hydrogen sulphide on liquid bromine with forma-
*G. S. Newth, Chem. News, 64, 215.
f E. Leger, Compt. rend. 115, 946-948.
% A. Gassman, Chem. Centr. 1893, i., 771-
INORGANIC PREPARATIONS. 12 1
tion of gaseous hydrogen bromide and solid sulphur de-
velops + 144 cal, without taking into account the heat
developed by the combination of the sulphur with the
excess of bromine.
Hydrogen sulphide is bubbled through a layer of
bromine contained in a tall, narrow vessel, and covered
by a layer of water or hydrobromic acid. The gas passes
into a second flask which contains a solution of potassium
bromide in hydrobromic acid holding a small quantity of
red phosphorus in suspension, and the gas which issues
from this flask contains neither bromine vapor nor hydro-
gen sulphide. The current of hydrogen bromide is con-
trolled by regulating the current of hydrogen sulphide.
The latter gas should be made in a " continuous "
apparatus.*
Although concentrated sulphuric acid decomposes po-
tassium bromide with liberation of bromine, when a more
dilute acid is used there is no evolution of bromine. To
obtain pure hydrobromic acid, 150 c. c. of sulphuric acid
of 1. 41 sp. gr. is poured on to IOO grams of coarsely pow-
dered potassium bromide, and the mixture warmed gently
and shaken until the salt is dissolved. The liquid is then
submitted to distillation ; it begins to boil at about 1260 C,
and the temperature slowly rises to 150° C, at which point
almost the whole of the hydrobromic acid passes over; then
the temperature rapidly goes up to 200 ° C, and traces of
sulphuric acid are mechanically carried over. The process is
now stopped, as between 2000 and 2500 C. only small quan-
tities of hydrobromic acid, mixed with a little sulphuric
acid, pass over. The distillate is redistilled, collecting only
A. Recoura, Compt. rend., no, 784.
122 LABORATORY MANUAL OF
what passes over at 126° C. ; this has a specific gravity of
1.49, contains 48 per cent, of HBr, is colorless, and con-
tains neither sulphuric acid, sulphurous acid, nor bromine.
150 grams of bromide yield about 200 grams of acid. If
the bromide contains bromate, the receiver is changed when
the distillate become colorless ; the acid thus obtained con-
taining bromine is treated with a little sodium sulphite, and
rectified with the rest. Gaseous hydrobromic acid may be
obtained by distilling the solution containing 48 per cent,
from anhydrous calcium bromide.*
HYDROGEN IODIDE.
HI.
In preparing hydrogen iodide from iodine and amorphous
phosphorus the iodine is placed in a flask provided with a
bent neck and connected with the vessel containing the phos-
phorus and water by means of a bent tube. By turning
the flask round the bent tube, fresh quantities of iodine
can be added when requisite without admitting air into
the apparatus. t
Another method of preparation is to moisten 1 00 parts
of iodine contained in a retort with about 10 parts of water.
The retort is then fitted with a funnel closed with a glass
rod, containing 5 parts of amorphous phosphorus mixed
with 10 parts of water. One drop of water containing phos-
phorus is let into the retort ; more phosphorus is slowly
*By W. Feit and K. Kubierschky, J. Pharm. [5], 24, 159; from
Pharm. Zeit. Russ., 30, 298.
f A. ETARD, Bull. Soc. Chirn. 49, 742.
INORGANIC PREPARATIONS. 123
added, after which large amounts may be used. The mix-
ing is complete in 15 minutes. If more than a drop is
added at first the action cannot be controlled, and will
generally result in a violent explosion. No heating is
necessary. The iodine carried over by the hydrogen
iodide is nearly all deposited in the neck of the retort,
which is inclined upward. By using 100 grams of iodine,
5 grams of phosphorus and 25 c. c of water, 95 grams
of hydrogen iodide (of which 37.5 grams were obtained by
distillation) are obtained, instead of 100.8 grams. With
20 grams of water 98.1 grams are obtained (74.4 grams
as gas and 23.7 grams by distillation).*
IODINE PENTOXIDE.
I2O5.
30 grams iodine are placed in a retort and 158 c. c.
of anhydrous nitric acid free from nitrogen oxides (page 18)
poured over it. On shaking a reaction takes place which
is hastened by moderate heating. The red vapors are
driven out by a strong current of air, which is blown into
the tubulature of the retort through a glass tube. In spite
of this a part of the iodine is invariably reduced by these
nitrogen oxides ; it volatillizes and is condensed with the
distilling acid in a receiver, which is kept cool. At inter-
vals the heating is stopped and the distillate, after having
air blown into it, is put back. The white residue is dis-
solved in a little water and evaporated to dryness in a
porcelain dish, iodic acid anhydride remaining in white
crystals.
* H. I. L. Meyer, Ber. 20, 3381.
124 LABORATORY MANUAL OF
IODINE TRICHLORIDE.
IClfr
20 grams iodine are gently heated in a small retort, the
bent neck of which terminates in a weighed balloon filled
with chlorine ^and closed, but connected with a Kipp's
chlorine apparatus. As soon as the iodine vapors enter
the balloon a strong absorption of chlorine takes place, and
iodine chloride precipitates against the walls in reddish-
yellow crystals. Finally dry carbonic acid is led through
to drive out the surplus chlorine. Any particles which
cannot be removed from the balloon mechanically are dis-
solved in ten times their weight of water, and preserved as
iodine chloride solution.
Iodine trichloride is an orange-colored pungent crys-
talline powder, readily soluble in water to a clear yellow
liquid. Chloroform should not remove iodine from the
aqueous solution until a little stannous chloride has been
added. On heating, the iodine trichloride should change
without leaving any residue into brown vapors, which con-
dense again to an orange- colored sublimate.
HYDROCYANIC ACID.
HCN.
500 grams coarsely powdered potassium ferricyanide are
distilled on the gas stove in a well ventilated place, with a
mixture of 350 grams cone, sulphuric acid and 700 c. c. water.
With the condenser twoWoulff bottles are connected; these
INORGANIC PREPARATIONS. 1 25
stand on ice ; the vapors escaping from the last bottle are
led into cold water. The insoluble residue* forming in the
retort causes a slight jolting of the contents, but by heat-
ing uniformly and carefully no danger need be feared.
The distillate is almost pure. If absolutely anhydrous
hydrogen cyanide is required, fill the first of the Woulflf
bottles before distillation half-way with porous calcium
chloride, and at the conclusion set it in warm water, in order
to distill its contents into the second bottle. The product
should not be preserved in an anhydrous, but in a diluted
condition ; the aqueous hydrocyanic acid keeps still better
if one drop of diluted mineral acid is added to every 100
c. c.
The anhydrous hydrocyanic acid is a very volatile,
colorless liquid, which when brought in contact with the
skin produces a cold feeling, like evaporated ether. It
boils at 270 C. and crystallizes in a freezing mixture. The
aqueous solution does not redden litmus paper, f
PURIFICATION OF HYDROFLUORIC ACID.
HF.
The apparatus employed for distilling commercial hy-
drofluoric acid consists of a heavy sheet-lead retort, 6 inches
high and 4 inches in diameter, with a rim at the top formed
by beating the lead over an iron ring 1 inch deep and ^
inch thick ; the lid is of ^ inch iron plate, covered with
lighter sheet lead, and is fixed down by a screw working in
a socket in an iron bridge, which is secured to projections
* This residue may be used in the preparation of Berlin Blue.
f Wohler, Annalen, 73, 219.
126 LABORATORY MANUAL OF
on the opposite sides of the iron ring of the rim. A washer
of india-rubber is placed between the cover and the rim.
The leaden nose of the retort points upwards, and is con-
nected by india-rubber tubing to a Liebig condenser, the
inner tube of which is of thin india-rubber. The retort is
charged through a funnel with 25 per cent, hydrofluoric
acid, which yields a distillate of convenient strength for
analytical work. The first portions of the distillate con-
tain silicate and are discarded, whilst any sulphur is re-
moved by filtration.*
STANNOUS CHLORIDE.
SnCte, Crystallized + 2H2O.
Reduce grain tin to powder by means of a file, or by
fusing it in a small porcelain dish, removing from the
fire, and triturating with a pestle until it has passed again
to the solid state. Boil the powder for some time with
concentrated hydrochloric acid and a few drops of platinic
chloride in a flask (taking care always to have an excess of
tin in the vessel) until hydrogen gas is scarcely evolved ;
dilute the solution with 4 times the quantity of water
slightly acidulated with hydrochloric acid, and filter. Keep
the filtrate for use in a well-stoppered bottle containing
small pieces of metallic tin, or some pure tin-foil. If these
precautions are neglected the stannous chloride will soon
change to stannic chloride, with separation of white oxy-
chloride, which will render the reagent unfit for use.
* By R. Hamilton, Chem. News, 60. 252.
INORGANIC PREPARATIONS. \2J
A solution of stannous chloride must, when added to
excess of solution of mercuric chloride, immediately pro-
duce a white precipitate of mercurous chloride ; when treated
with hydrogen sulphide it must give a dark brown pre-
cipitate ; it must not be precipitated nor rendered turbid
by sulphuric acid.
ANHYDROUS STANNOUS CHLORIDE.
SnC12.
Commercial stannous chloride is heated slowly on the
gas stove ; the salt melts in its water of crystallization, then
becomes pasty, and gradually entirely solid. The dehy-
drated salt is fused once more, and in cooling it is
placed in a mounted retort of hard Bohemian glass, the
upper part of which is covered with a cap of wire gauze or
asbestos, to avoid too strong radiation, and distilled as
quickly as possible into a porcelain dish, which is kept
covered, with a second dish. As the stannous chlo-
ride boils at about 3270 C. the heat must be very
strong ; a small blow-pipe furnace will serve as the best
source of heat. The neck of the retort is heated with a
Bunsen burner, so it will not choke up with the solidifying
distillate.
Anhydrous stannous chloride is a white, crystalline
mass, melting at 2500 C, dissolving readily in water, alcohol,
ether and soda lye.
ANHYDROUS STANNIC CHLORIDE.
SnCl^.
150 grams pure tin (granulated or in bars) are heated
to fusion on the gas stove in a mounted, tubulated retort,
128 LABORATORY MANUAL OF
and a strong stream of dry chlorine led into it through a
glass tube opening near the surface of the fused metal.
The retort connects with a very long condenser and two
WoulfF bottles as receivers. The receivers are placed in
ice- water, to hasten the condensation of the very volatile
chloride. The chloride collected is distilled from a frac-
tional distilling flask containing a little tinfoil.
Sn -j- 4C1 == SnCl4. The free chlorine combines with
the metallic tin during the rectification.
Anhydrous stannic chloride is a colorless solution,
boiling at 114° C, fuming strongly when exposed to air,
of 2.278 sp. gr. at o° C, with a small amount of water, it
furnishes crystalline compounds, but dissolves completely
in a larger quantity of water.
PHOSPHORUS
FROM
PHOSPHATES OF THE ALKALIES AND ALKA-
LINE EARTHS BY MEANS
OF ALUMINIUM.
When sodium metaphosphate is heated with aluminium
in a current of hydrogen, 28 to 3 1 per cent, of the phos-
phorus distills over, and a residue is obtained consisting of
alumina, sodium aluminate, and aluminium phosphide. All
the phosphates of calcium and magnesium, when heated
with aluminium, yield phosphorus.
Aluminium phosphide, A13P5 is obtained by heating
aluminium in phosphorus vapor, and then heating the
product until phosphorus ceases to come off. It is a gray
crystalline powder.
INORGANIC PREPARATIONS. I 29
The whole of the phosphorus in the phosphates may
be obtained by adding silica to the mixture in the propor-
tions represented by the equation :
3Ca(P04)2 + 10A1 + 3Si02 - 3CaSi03 + 5A1203 + 3P3.
When a mixture of calcium metaphosphate and calcium
sulphate is heated with aluminium, a violent explosion
ensues. It has been found that this is due to the sulphate.
Barium sulphate or calcium sulphate, when heated with
aluminium, act with explosive violence and sulphur is set
free. The chlorides are also decomposed by aluminium at
a high temperature.*
PURE PHOSPHORIC ACID FROM SODIUM
PHOSPHATE.
H3PO4.
Crystals of hydrogen sodium phosphate are subjected
to the action of gaseous hydrogen chloride. In this man-
ner syrupy phosphoric acid in amount corresponding with
a yield of 75 per cent, of the theoretical quantity is
obtained t
Pure phosphoric acid may also be obtained when pow-
dered calcium phosphate is added gradually to a slight
excess of commercial hydrofluoric acid diluted with an
equal volume of water, and contained in a leaden or plati-
num vessel. There is considerable development of heat,
and the liquid must be thoroughly agitated. When the
* A. Rossel and L. Frank, Ber. 27, 52.
f G. Watson, J. Soc. Chem. Ind. 2, 224.
9
I30 LABORATORY MANUAL OF
action moderates, the liquid is gently heated, water being
added to make up for loss by evaporation. When the
liquid becomes viscous, the excess of hydrogen fluoride
begins to escape, and the mixture is then heated until the
expulsion of the acid is complete. The syrupy liquid thus
obtained contains from 60 to 70 per cent, of phosphoric an-
hydride in the form of orthophosphoric acid. With pure
materials, the phosphoric acid obtained is very pure ; if
bones and ordinary acid have been used the product must
be heated to carbonize the organic matter, dissolved in
water, filtered, and again evaporated. Pyrophosphoric and
metaphosphoric acids can be obtained by evaporating at
higher temperatures.*
Another method is to heat 127 grams white phosphor-
us with 1400 c. c, nitric acid (1.20 sp. gr.) in a retort with
receiver. The phosphorus melts, and then the operation
quietly proceeds. At intervals the distillate must be poured
back. When the phosphorus has passed entirely into solu-
tion (after 10 to 12 hours) it is evaporated in a platinum
dish until a sample taken out with a glass rod together with
cone, sulphuric acid and ferrous sulphate solution ceases to
give a reaction for nitric acid. The temperature must not
exceed 1 88° C. The acid when mixed with mercuric chlor-
ide solution must show no trace of phosphorus acid. After
this, it is treated warm with sulphureted hydrogen until on
standing there is no further precipitate of arsenic sulphide,
then diluted with a little water, filtered, and again slowly
evaporated, until a thermometer dipped into it shows
160 C.
*M. Nicolas, Compt. rend., in, 974.
INORGANIC PREPARATIONS. 131
The acid should show a sp. gr. of 1.88, and be free
from arsenic and phosphoric acid.
PHOSPHORUS TRISULPHIDE.
P2S3.
310 grams red phosphorus are mixed with 480 grams
powdered sulphur and the powder poured by spoonfuls
into a hessian crucible which has been heated on a Bunsen
burner. After adding each portion, the crucible is closed
with a cover whereupon the reaction should take place at
once. When the whole mixture has been added, the cruci-
ble is allowed to cool sufficiently to leave the mass soft,
and then the phosphorus sulphide is poured out on a piece
of sheet-iron. The solid product is broken in pieces while
warm and placed in a well-stoppered bottle. Phosphorus
trisulphide forms in a hard, gray, easily powdered mass,
which when exposed to air becomes moist and smeary, de-
veloping sulphureted hydrogen.
CALCIUM PHOSPHIDE.
CaP.
To a strong clay crucible, about 6^ cm. wide and 12
cm. high, fit a round cover of sheet-iron 2 mm. thick pro-
vided with a round opening in the center of 2.5 mm.
diameter and into which is fitted an iron tube 30 cm. long.
At the upper end of this iron tube, a thin walled glass
32
LABORATORY MANUAL OF
■
tube of 1 5 cm. in length is fastened.* Fig. 9. After having
placed the iron tube perpendicularly in the crucible, the
latter is filled with 100 grams burnt marble or lime in
pieces the size of a hazel nut. Cover the cruci-
ble and then heat in Roessler's annealing furnace.
When the crucible has become red-hot, 65 grams
of dry phosphorus in sticks are dropped into it
through the glass tube, in pieces of about 5 to 10
grams. Immediately upon dropping each piece
of phosphorus the glass tube is closed with a
cork provided with a handle. The influence of
phosphorus on the lime is manifested each time
by the escape of a little phosphorus pentoxide
in form of a white cloud of smoke from the
chimney of the furnace. If this reaction fails
to take place, the iron tube is raised a little,
allowing the phosphorus to enter into the cruci-
ble. While at first only minimum quantities
escape reaction, the conclusion of the operation
is shown by the appearance of thick smoke.
The flame is then extinguished, the crucible taken out, and
the product immediately upon having cooled (still slightly
warm) is filled into a well-closed specimen cylinder.
7CaO -f 7P = Ca3P307 + 5CaP. Calcium phosphide
forms in dark, hard, rainbow-colored pieces, which when
thrown into warm water develop phosphureted hydrogen :
2CaP + 4H30 = 2Ca (OH)8 4- P2H4. \
* For this purpose wind a little thin asbestos cord around the glass tube,
then twist it into the iron tube, after having moistened the asbestos with
water glass. The joints are covered with a pasty mixture of powdered
oxide manganese and water glass, then dried at moderate heat. The glass
tube must be sufficiently wide to conveniently allow the passage of the
phosphorus sticks.
f Gattermann and Haussknecht, Ber. 23, 1175.
Fig. 9.
INORGANIC PREPARATIONS. 1 33
PHOSPHORUS OXY FLUORIDE.
Zinc carbonate is dissolved in excess of hydrofluoric
acid, the solution evaporated, and the zinc fluoride dried
at 3000 and placed in a brass tube, to which a bromine
burette, containing slight excess of the calculated quantity
of phosphorus oxychloride, and a leaden delivery tube are
adapted by a paraffined cork. The leaden tube is connected
to another brass tube cooled by a freezing mixture to 20° C,
and this leads to another tube containing zinc fluoride,
which removes any traces of oxychloride escaping from
the oxyfluoride. The phosphorus oxychloride is dropped
slowly on to the zinc fluoride, the ensuing reaction being
assisted by warming carefully at 40 to 500 C, and the
evolved gas is collected over mercury in glass vessels.*
HYDROGEN PHOSPHIDE.
PH3.
Tin and zinc phosphides are prepared by adding the
equivalent quantity of amorphous phosphorus to the re-
spective metals in the molten state covered with ammo-
nium carbonate. Iron phosphide, FeP, by heating finely
divided iron and amorphous phosphorus together, copper
phosphide, by heating copper filings with amorphous phos-
phorus ; magnesium phosphide, by adding the equivalent
quantity of amorphous phosphorus to melted magnesium ;
sodium phosphide by carefully adding yellow phosphorus
* By H. Moissan, Bull. Soc. Chim. [3], 4, 260.
134 LABORATORY MANUAL OF
to fused sodium under petroleum. The phosphides of tin,
zinc, iron, and copper are not decomposed by water ;
whilst those of sodium and magnesium, like that of calcium
are decomposed by water. From magnesium phosphide,
whether decomposed by water or by dilute hydrochloric
acid, non-spontaneously inflammable hydrogen phosphide
is obtained. From sodium phosphide, spontaneously in-
flammable hydrogen phosphide is obtained, which, in a
great measure, readily changes to solid phosphide. The
phosphides of tin and zinc are decomposed by cold dilute
hydrochloric or sulphuric acid, but those of iron and cop-
per are but slightly attacked even on boiling.
For the preparation of hydrogen phosphide from the
phosphides of tin, zinc or magnesium, an Erlenmeyer flask
of 200 to 300 c. c. capacity is fitted with a stopper carrying
three tubes, one of which conducts carbonic anhydride gas to
the bottom of the flask to displace the air, the second ad-
mits the dilute acid from a tap-funnel, the third is the
delivery tube. To the latter is attached a tube, filled with
glass wool, from which the gas passes out into nitric acid
in a dish. In the case of tin phosphide the flask is warmed
gently on the water-bath at the commencement, after which
the reaction proceeds regularly for thirty minutes to one
hour, when as the reaction becomes slower, the flask may
again be warmed. In the case of zinc or magnesium phos-
phides, no external heating is requisite. The method is
preferable to the preparation with potassium hydroxide and
phosphorus or to that with calcium phosphide, and demon-
strates the formation of the phosphide of hydrogen in
analogous manner to the other compounds of hydrogen
with the non-metals, ammonia excepted. The preparation
INORGANIC PREPARATIONS. I 35
of zinc phosphide is also especially recommended as being
simple. The synthesis of hydrogen phosphide may be
shown by placing sodium phosphite or hypophosphite into
a hydrogen generator, when the phosphide is readily de-
tected in the gas evolved.*
ARSENIC ACID.
H3As04.
The arsenic acid liquid produced in preparing nitrogen
tetroxide (page 2 i ) is poured off from the unchanged pieces
of white arsenic, evaporated to dryness in a porcelain dish,
and the residue again dissolved by heating with a little
water. The solution must be free from arsenious acid, or
else must be again evaporated, adding a little H2S04, and
dissolved once more. If the solution is pure it is boiled
down to a syrup, and left to crystallize at a low tempera-
ture in a closed vessel, adding, if necessary, a small crystal
of arsenic acid. When the concentration is perfect, very
nice, large, compact glossy crystals will be obtained ; if the
crystallization has occurred too quickly, the mass is dis-
solved, the crystals are melted at a moderate heat, and
then allowed to slowly crystallize, so that larger crystals
may be obtained.
Arsenic acid should dissolve readily in water, and
with ferrous sulphate give no nitric acid reaction. The
well-diluted solution mixed with a drop of HC1 should
at first remain clear; when mixed with an equal volume
* By R. Luepke, Chem. Centr., 1890, i i, 642 ; from Zeit. f. physikal
und chem. Unterricht, 3, 2 So.
136 LABORATORY MANUAL OF
of sulphureted hydrogen water should only become tur-
bid upon standing some time. A solution of the acid
in fuming HC1 should immediately give a thick yellow
precipitate with hydrogen sulphide.
2HN03 + As303 4- 2H20 = N203 4- 2H3As04. Arsenic
acid is not precipitated from aqueous solution by hydrogen
sulphide, but from cone, hydrochloric acid solution ; it is
at once precipitated, when a mixture of arsenic pentasul-
phide, sulphur and arsenic trisulphide is thrown down. In
such a solution arsenic pentachloride, which is unknown in
a pure condition, seems to be present, and this is decom-
posed by hydrogen sulphide according to the equations :
2AsCl5 4- 5H3S = As2S5 + 10HC1;
AsCl5 -f H2S = AsCl3 + S + 2HC1;
2AsCI3 + 3H0S = As2S3 + 6HC1.
HYDROGEN ARSENIDE.
H3As.
The action of zinc on an acid solution of arsenious acid
produces a gas containing 70 per cent, by volume of hy-
drogen arsenide. Sodium amalgam containing not more
than 4 grams of sodium in 50 c. c. of mercury, by its action
on a concentrated solution of arsenious acid, produces a
gas containing 86 per cent, by volume of hydrogen arsenide.
A gas containing a large quantity of arsenic may be pre-
pared by the action of aluminium on a somewhat dilute
alkaline solution of potassium arsenite, while a solution of
arsenic disulphide in potash, when subjected to the action
of aluminium, evolves a gas quite free from arsenic*
* A. Kavazzi, Rend. Ace. Bologna, 1886-7, 85.
INORGANIC PREPARATIONS. I 37
ARSENIC PENTASULPHIDE.
As2 S5.
When a solution of an alkaline arsenate, strongly acidi-
fied with hydrochloric acid and saturated with hydrogen
sulphide is heated in a closed vessel at ioo° C. for one
hour the arsenate is completely converted into pentasul-
phide. It contains no trisulphide, and if due precau-
tions have been taken to exclude air, no free sulphur.
Pure arsenic pentasulphide is lemon yellow in color,
does not yield any sulphur to carbon disulphide, and
dissolves in ammonia without separation of sulphur.
When the ammoniacal solution is agitated with silver nitrate
and filtered a clear nitrate is obtained, from which nitric
acid precipitates silver arsenate. Arsenical pyrites may
oe used instead of alkaline arsenate, in which case the
finely pulverized ore is digested for some time in aqua
regia until decomposed ; the chlorine is boiled out and hy-
drogen sulphide passed through the cold solution as long
as a precipitate forms ; this serves to remove heavy
metals, as sulphides ; filter and wash with hydrogen sul-
phide water, saturate with hydrogen sulphide, and pro-
ANTIMONY TRICHLORIDE.
SbCl3.
100 grams powdered stibnite are heated with 500 c. c.
crude HC1 in a flask, gradually adding about 4 grams po-
tassium chloride. When the ore has disappeared filter off
* L. W. McKay, Chem. News, 54, 287.
I38 LABORATORY MANUAL OF
from the sulphur through glasswool, and distill out of the
retort ; at first aqueous hydrochloric acid comes over, then
a concentrated antimony chloride solution, which is fre-
quently of a yellow color from iron chloride, finally nice
white, pure antimony chloride, cooling in crystals, will pass
over. Each of these products are caught up separately.
The pure antimony chloride is refined in a test tube or
small flask, the antimony chloride solution decomposed by
a large quantity of water, whereby antimony oxychloride
is precipitated as a fine white powder (Algaroth).
The change Sb2S3 + 6HC1 = 2SbCl8 + 3H3S which at
first goes on energetically, but gradually becomes very
slow, and may be hastened to a conclusion by adding the
means of oxydation.
The antimony chloride should melt at 73° C, boil at
2230 C, and crystallize from carbon disulphide in rhombic,
glossy crystals.
ANTIMONY OXYCHLORIDE.
Sb405Cl2.
60 grams powdered antimony sulphide are thoroughly
mixed in a mortar with 140 grams mercuric chloride, and
slowly distilled from a gas retort over the gas stove at
gentle heat. A flask is used as receiver, the neck of which
has been broken off; the neck of the retort is heated at in-
tervals with a Bunsen burner, to melt the antimony chlo-
ride that solidifies in it. The distillate is dissolved in a
little warm HC1, and then poured into a large quantity of
INORGANIC PREPARATIONS. 1 39
hot water ; the precipitate is washed by decantation and
then dried.
Sb2S3 -f 3HgCl2 = 2SbCl3 + 3HgS,
4SbCl3 + 5H20 = Sb405Cl2 + 10HC1.
The white crystalline powder should be insoluble in
water, alcohol and ether, but soluble in carbon disulphide
and chloroform. On heating it should give a sublimate
of antimonious chloride, leaving behind antimony mon-
oxide.*
ANTIMONIOUS SULPHATE.
Sb2(S04)3.
20 grams finely powdered antimony are added to 400
grams of boiling, distilled H2S04 and boiled in a platinum
dish until the metal has disappeared. A part of the sul-
phate crystallizes out of the hot solution, the rest upon the
cooling of the liquid, in the form of small white needles. It
is filtered through a platinum cone and dried on an earthen
plate.
BISMUTH NITRATE.
Bi(N03)3 + 5H20.
BASIC BISMUTH NITRATE.
BiON03 + BiOOH.
BISMUTH HYDROXIDE.
B.OOH.
100 grams commercial bismuth and 50 grams sodium
nitrate are heated in a nickel dish at faint red-heat. After
* G. E. Stahl, Zufallige Gedanken und nutzliche Bedanken uberden
Streit von den sogennaten sulfure Halle, 1715, S. 346.
I40 LABORATORY MANUAL OF
the metal is completely oxydized boil thoroughly with 250
c. c. water, adding a solution of 20 grams sodium hydrate
in 150 c. c. water. The bismuth oxide filtered on the
bare platinum cone is dissolved hot in a flask containing
a mixture of 140 c. c. cone. HN03 with 200 c. c. water, fil-
tered through an asbestos filter and evaporated to crystal-
lization. The mother liquid is evaporated further, and
poured into y2 litre boiling water, whereupon the basic bis-
muth nitrate separates in the form of a heavy white powder,
which, after decanting, is collected on the filter and dried
in the cold ; or else the acid solutions are precipitated
with ammonia, the bismuth oxyhydrate decanted and pre-
served as a paste.
The impurities of commercial bismuth consist chiefly
of arsenic and antimony, the oxides of which go into
solution upon boiling with soda.
The bismuth value of the crystallized nitrate should
be ascertained from a weighed sample by converting it
into bismuth oxide in a covered porcelain crucible, heat-
ing at first carefully, then energetically. Further, a sample
is dissolved in very dilute nitric acid, the solution poured
into an excess of hot soda, and the filtrate tested for arsenic
and antimony.
BISMUTH IODIDE.
Bil3.
20 grams iodine are mixed with 35 grams finely pow-
dered bismuth in a mortar, quickly poured into a retort,
and slowly heated on the gas stove. When the reaction
is finished the small quantity of surplus iodine is driven out
INORGANIC PREPARATIONS. I4I
by a current of dry carbonic acid gas, and the temperature
raised until the bismuth iodide sublimes in form of very
large crystals, similar in appearance to iodine.
Boiling water should convert the powdered bismuth
iodide into red oxyiodide.
BISMUTH OXYIODIDE.
BiOI.
95.4 grams powdered crystallized bismuth nitrate
(page 139) are dissolved in 120 to 160 c. c. glacial acetic
acid by warming gently. At the same time 33.2 grams
potassium iodide and 50 grams crystallized sodium acetate
are dissolved in 2 litres cold water. The second solution
is placed in a dish and the first added to it in a very thin
stream from a dropping funnel, with frequent stirring. At
the point where the liquid strikes a greenish-black pre-
cipitate forms at first ; upon stirring this immediately
changes to a lemon color. On further addition of the
bismuth solution the product assumes a dark, brick-red
color. The precipitate settles very readily. It is decanted,
filtered and dried at ioo° C.
Bi(N03)3 -f 3KI = Bil8 4- 3KN03;
Bil3 + H20 = BiOI {-2HI.
The hydriodic acid reacts with the sodium acetate,
and the potassium iodide formed again takes part in the
reaction.
Heated in a dry test-tube the compound should yield
violet iodine-vapors, and leave behind bismuth oxide ; on
shaking with water no halogen acid should be set free,
142 LABORATORY MANUAL OF
and it should be free from arsenic and bismuth subnitrate :
0.2 gram shaken with 2 grams dilute sulphuric acid
should give a filtrate which, when mixed with twice its
volume of cone. H2SO4, should be permanently colored blue
by a drop of indigo solution (discoloration nitric acid).*
BISMUTHIC ACID.
HBi03.
20 grams of bismuth bromide and 40 grams of potas-
sium bromide are dissolved in 60 grams of water and
mixed with excess of bromine. The solution is then
poured drop by drop into an almost boiling solution of 100
grams of potassium hydroxide in 150 grams of water, the
alkali remaining in excess at the end of the reaction. A
very dense red-brown precipitate forms immediately. This
is washed repeatedly with boiling water by decantation,
and, after along time, part of the product forms a brown
emulsion with the water, whilst a red-brown compound
remains at the bottom of the vessel. The emulsion is de-
canted off, and can be precipitated by addition of a few
drops of nitric acid. The non-emulsified product is
washed with hot water until no longer alkaline, and one
portion is washed for several days longer. Both portions,
when dried at ioo° C, have the composition 4KBi03,
3HBi03. The same product is obtained from bismuth
chloride ; it dissolves easily in hydrochloric acid, with
evolution of chlorine, but is soluble only with difficulty in
warm nitric acid. When heated it becomes pale-yellow,
* B. Fischer, Die neueren Arzeneimittel, III. Aufl., s. 20.
INORGANIC PREPARATIONS. I43
loses oxygen, then becomes brown, melts, and on cooling
is pale-yellow.
Prolonged washing with boiling water yields a product
which, after being dried at ioo° C, has the composition
KBi03,HBi03.
All these products when treated with warm, dilute
nitric acid lose the whole of their potassium, and yield
brick red bismuthic acid, HBiOs. Very often the residue
dried at ioo° C. has the composition HBi03,Bi205.*
ANTIMONY AND BISMUTH SULPHATES.
Anhydrous antimony sulphate, Sb2(S04)3, is best pre-
pared by dissolving the trisulphide in concentrated sul-
phuric acid heated to the temperature at which it com-
mences to vaporize ; the salt is deposited as a fine, very
deliquescent, white crystallized powder. Its products of
decomposition with water vary with the conditions, such
as mass and temperature ; with boiling water the salt is
completely decomposed into antimonious oxide (contain-
ing less than I per cent, of water) and sulphuric acid, whilst
with water at ordinary temperatures a basic sulphate,
5SB2032S037H20, is produced. The sulphate is almost
completely converted into antimonious chloride by a cur-
rent of hydrogen chloride. Anhydrous bismuth sul-
pliate, Bi2(S04)3, prepared in a manner similar to the
antimony salt, crystallizes in very hygroscopic, glis-
tening needles ; when evaporated with water it yields a
* G. Andre, Compt. Rend., 113, 860-862.
144 LABORATORY MANUAL OF
slightly coherent powder of the composition Bi2(S04)3 +
3H20, but on heating it with water at the ordinary tem-
perature, and evaporating the solution, a powder of the
composition 2Bi2(S04)3 + 7H20 is obtained ; lastly, if the
salt be frequently treated with water, the final product is
a hydrate, Bi2,03,S03,H20. It is probable that tinder
favorable conditions the sulphate is converted by hydro-
chloric acid into bismuth trichloride.*
COBALT NITRATE.
Co(N03)2, Crystallized + 5H20.
Fuse in a Hessian crucible 3 parts of potassium disul-
phate, and add to the fused mass, in small portions at a
time, 1 part of well-roasted cobalt ore (the purest zaffre
you can procure) reduced to fine powder. The mass
thickens and acquires a pasty consistency. Heat now
more strongly until it has become more fluid again, and
continue to apply heat until the excess of sulphuric acid is
completely expelled, and the mass accordingly no longer
emits white fumes. Remove the fused mass from the
crucible with an iron spoon or spatula ; let it cool and
reduce it to powder ; boil this with water until the undis-
solved portion presents a soft mass ; then filter the rose-
red solution, which is free from arsenic and nickel and
mostly also from iron. Add to the filtrate a small quantity
of sodium carbonate, so as to throw down a little cobalt
carbonate ; boil and filter. Precipitate the solution, which
is now free from iron, boiling with sodium carbonate; wash
the precipitate well, and treat it still moist with oxalic
C. Hensgen, Rec. Trav. Chim.,4, 401-413.
INORGANIC PREPARATIONS. 1 45
acid in excess. Wash the rose-red cobalt oxalate thor-
oughly, dry and heat to redness in a glass tube, in a cur-
rent of hydrogen gas. This decomposes the oxalate into
carbonic acid gas, which escapes, and metallic cobalt, which
is left behind. Wash the metal first with water containing
acetic acid, then with pure water; dissolve in dilute nitric
acid, treat, if necessary, with hydrogen sulphide, filter the
fluid from the copper sulphide, etc., which may precipitate,
evaporate the solution in the water-bath to dryness.
Solution of cobalt nitrate must be free from other
metals, and especially from salts of the alkali metals ;
when precipitated with ammonium sulphide and filtered,
the filtrate must, upon evaporation on platinum, leave no
fixed residue.
HYDROGEN PEROXIDE.
H203.
One-half litre commercial hydrogen peroxide is cooled
in a flask to o° C. and mixed with a cold, saturated barium
hydrate solution until a permanent precipitate forms, and the
solution has become alkaline. The filtered solution, cooled
and shaken, is allowed to flow into 2 litres of ice-cold
barium hydrate solution. When the crystalline precipitate
no longer forms, the peroxide is filtered and rinsed with a
little ice- water. Now 20 c. c. cone. H2SO4 are mixed with 200
c. c. water, the solution carefully cooled in a freezing mix-
ture of ice and common salt, and enough of the still moist
barium peroxide added, shaking, until the solution reacts
only faintly acid. Then it is allowed to settle ; the ice-
cold solution is filtered and neutralized with a few drops
I46 LABORATORY MANUAL OF
of dilute barium hydrate, until neither H3S04 nor barium
remains in the solution. Then the turbid solution is fil-
tered, and a part of the thus obtained pure hydrogen per-
oxide solution evaporated on a porcelain plate in vacuum
over H3S04.
The reactions: H303 + Ba(OH)3 = Ba(OH)4 and
Ba(OH)4 + H3S04 = BaS04+ H303 will only take place in
the cold and in not too high concentration. If these con-
ditions are not fulfilled, oxygen developes richly, and the
gain will prove a minimum.
The anhydrous peroxide should be a syrupy, bitter-
tasting solution of 1.46 sp. gr., which on warming decom-
poses readily. The watery solution should also have the
peculiar characteristic taste ; and yield, when mixed with
dil. sulphuric acid, ether and a drop of dilute potassium
dichromate solution, an intense blue, ether-soluble color;
be free from HC1,H2S04 and barium. One per cent, of
alcohol is added for preservation.
The value is determined by decomposing 1 c. c. hydro
gen peroxide solution with excess of permanganate of potas-
sium and dil. H3S04 in a nitrometer, or else by titration
of 5 c. c. with -±q normal permanganate in sulphuric acid
solution.*
Another method for the preparation of pure hydrogen
peroxide is to take the solution of hydrogen peroxide
which results from the action of hydrochloric acid (sp. gr.
1.1) on barium dioxide, and is extracted by shaking with
ether; the ethereal solution is agitated with distilled water, to
which it yields the dissolved hydrogen peroxide. By repe-
titions of this process, a pure, neutral solution correspond-
* J. Thomsen, Ber. 7-74.
INORGANIC PREPARATIONS. I47
ing with 0.8 to 0.9 per cent, of hydrogen peroxide is obtain-
able, from which the dissolved ether may be eliminated by
distillation under reduced pressure.*
It can also be prepared by adding sodium carbonate
to the commercial 3 per cent, aqueous solution of hydro-
gen peroxide, until the reaction is distinctly alkaline. The
solution is then filtered, and shaken up for 3 to 5 minutes
with 10 to 12 times its volume of ether, which extracts
about half of the hydrogen peroxide originally present,
and leaves behind most of the impurities. The ethereal
layer is separated and reduced to 0.01 to 0.0025 of its
original volume on the water-bath. The remainder of
ether is removed in a bell jar by solid paraffin. The loss
of hydrogen peroxide during the evaporation of the ether
is only 7 to 10 per cent.
Operating in this way two solutions are obtained : (a)
a colorless solution with distinctly acid reaction, and sp. gr.
1. 1756, which contains 54 grams of anhydrous hydro-
gen peroxide in 100 c. c; (b) a thick transparent
slightly yellow, acid liquid, of sp. gr. 1.2475, which con-
tains 79.6 grams of hydrogen peroxide in 100 c. c.f
Hydrogen peroxide chemically pure can be prepared
by mixing hydrogen peroxide of commerce with 0.25 per
cent, of phosphoric acid and then while vigorously stirring,
barium hydroxide is added until the solution is neutral to
litmus. The clear solution is poured into a cold saturated
solution of barium hydroxide and the precipitate of barium
dioxide is well washed and may be kept for the prepara-
tion of pure hydrogen dioxide. For this purpose it is
* L. Crismer. Bull. Soc, Chim. [3], 6, 24-25.
\ P. Shiloff, J. Russ. Chem. Soc, 25, 293.
148 LABORATORY MANUAL OF
made into a thin magma and carefully decomposed by
dropping steadily into dilute sulphuric acid containing 12
per cent, of concentrated acid; and excess of sulphuric
acid being removed by hydroxide and vice versa. Excess
of barium dioxide must be avoided, as it decomposes hy-
drogen dioxide.*
POTASSIUM AND SODIUM PEROXIDES.
When potassium is dropped into molten potassium ni-
trate the metal burns with a bright light, with the forma-
tion of yellowish potassium peroxide which dissolves in the
fused mass, imparting to it a deep, rich red color. In a
similar manner sodium and sodium nitrate give rise to a
yellowish-red solution, whilst potassium and potassium
nitrate give a brown-red solution. In all cases the color
disappears on cooling, but on heating again reappears. The
aqueous solutions from the colorless masses give a greenish
precipitate with copper sulphate. The action of sodium
on fused potassium chlorate is attended with dangerously
explosive violence. t
SULPHUR MONOCHLORIDE,
S2CI2,
AND
SULPHUR DICHLORIDE,
SC12.
300 grams sulphur are heated to its melting point in a
tubulated retort over a low flame, and as in the case of tinte-
* Mann. Chem. Zeit., 12, 857.
f H. C. Bolton Chem. News, 53, 2S9-290.
INORGANIC PREPARATIONS. 149
trachloride a rapid stream of dry chlorine gas is passed
close to the surface of the melted sulphur. The vola-
tile chloride is redistilled in a side neck flask, and a
little dissolved sulphur remains as a residue. 67.5 grams
of the sulphur monochloride are cooled to o^ C. and
saturated with dry chlorine gas. The sulphur dichloride
so produced must weigh 103 grams. It is preserved in
well-stoppered bottles.
In the redistillation of the chloride of sulphur the
higher chlorides change into sulphur monochloride; on the
other hand at 0° C. sulphur monochloride combines with
another molecule of chlorine : S2C12 + Cl2 = 2SC12.
The sulphur monochloride should form a yellowish-red,
strong-smelling solution of 1.7 sp. gr., and the sulphur
dichloride a dark red solution, which should develop
chlorine at ordinary temperature the quantity increasing
with the temperature.
PREPARATION OF CHROMIUM FROM POTAS-
SIUM CHROMIUM CHLORIDE AND
MAGNESIUM.
Chromium can be quickly prepared in an almost chem-
ically pure condition in the following manner : Potassium
dichromate (100 grams) is dissolved in the least possible
quantity of water, the solution mixed with hydrochloric
acid of sp. gr. 1.124 (400 c. c), and then 80 per cent, al-
cohol (100 c. c.) gradually added. The solution of potas-
sium chromium chloride obtained in this way is treated with
potassium chloride (160 grams), the filtered solution evap-
I50 LABORATORY MANUAL OF
orated to dryness, the residue heated until anhydrous, freed
from the green portions, which are produced by the de-
composition of the double salt, then powdered, and mixed
with magnesium filings (50 grams). This mixture is heated,
for about half an hour, to a bright red heat, in a closed
Hessian crucible in a blast-furnace, care being taken that
the potassium chloride does not volatilize completely,
otherwise the chromium is partially oxidized. The melt is
separated from the superficial layer of chromium oxide,
treated with water, and the finely divided metal freed from
salts and unchanged magnesium by washing it with water;
then boiling it with dilute nitric acid, and again washing
with water, all the washing being done by decantation.
The yield of the metal, dried at iooQ C, is about 27 grams.
Chromium, prepared in this way, is a light-gray, crys
talline, non-magnetic powder of sp. gr. 6.7284 at i6p C.
it can be melted in a Deville's furnace, but only with great
difficulty, and after being melted it shows a silvery fracture.
Two analyses of the powder showed that it contained
99.53 to 99.57 per cent of chromium, and that it was free
from silver and magnesium.*
CHROMYL CHLORIDE.
Cr03Cl3.
200 grams neutral potassium chromate and 122 grams
common salt are melted in a Hessian crucible at a moder-
ate temperature, the fusion is poured on a piece of sheet-
* E. Glatzel, Ber. 23, 3127-3130.
INORGANIC PREPARATIONS. I 5 I
iron and broken in coarse pieces, these are digested with a
mixture of 66 c. c. fuming H2S04 (1.096 sp. gr.) and 134
c. c. ordinary cone, H2S04 in a roomy retort with con-
denser. The reaction is very violent at first ; when it mod-
erates, the retort is heated until no more brown drops
pass over, and the distillate is rectified in a fractional dis-
tilling flask. The chromyl chloride is preserved in sealed
tubes.
Cr03 + 2HC1— H30 = Cr02Cl3.
The dark red oxychloride which fumes when exposed
to the air should boil at 1 160 C.
ANHYDROUS CHROMIUM CHLORIDE.
CrCl3.
The chromium oxide obtained as per directions on
page 151, while still moist, is kneaded to a paste with 50
grams powdered coal and thick starch paste. Of this, bars
are formed which are cut in pieces of 2 to 3 cm. long. The
pieces, dried at a moderate heat, are packed with coal
powder in a Hessian crucible, covered with a layer of coal
powder, closed with an iron cover and ignited for 15
minutes in Roessler's furnace. Now a porcelain tube is
set upright in a Hessian crucible, the crucible filled with
the pieces of chromium oxide mixture which have been
cooled and separated from the surplus coal-powder, a sec-
ond crucible of the same size with perforated bottom is
placed upon it bottom up. A short glass tube passes
through a small hole bored in the side of the upper cruci-
152
LABORATORY MANUAL OF
ble. The tubes are wound with a little asbestos cord and
fit tight in the openings ; in order to make both crucibles
tight, a narrow, thin strip of soft asbestos board is wrapped
around the joint and carefully wound with
asbestos cord, finally the asbestos cord is
saturated with water glass and dried at
moderate heat. (See' fig. 10.) Then the
crucibles are placed in a Roessler's anneal-
ing furnace and this covered with two
semicircular pieces of thick sheet-iron
which have an opening in the center
through which the upper crucible appears.
It is first heated in a current of carbonic
acid until no trace of moisture is shown
on the glass tube. Then the strongest
heat is applied and it is ignited in a cur-
rent of chlorine, the uncombined chlorine
passes out through the glass tube and is
absorbed in soda.
Upon cooling the chromium chloride is found sublimed
in the upper crucible in violet-red very glossy scales which
are insoluble in water.
Cr303 + 3C + 6C1 = 2CrCl3 + 3CO.
Fig. 10.
CHROMIUM OXIDE.
Cr203.
250 grams potassium dichromateare thoroughly mixed
with 50 grams of sulphur placed in a clay crucible covered and
INORGANIC PREPARATIONS. 153
ignited for one hour in Roessler's annealing furnace. The
green contents of the crucible are ground, boiled several
times with water, filtered and dried.
K2Cr207 + S = K2S04+ Cr203.
Only traces of the green powder should go into solu-
tion on boiling it with dilute hydrochloric acid.
CHROMIUM ACETATE.
(CH3COO)2Cr.
500 grams fuming HC1 are poured over IOO grams po-
tassium dichromate in a flask, and the chlorine gas, which
develops, upon warming, after being washed with water, is
used in the preparation of chlorine water or of hypo-
chlorite of sodium. The remaining solution is evaporated
to a very small volume, poured off from the separated po-
tassium chloride into a flask with 300 grams of granulated
zinc and rinsed with 400 c. c. fuming HC1. The flask, in
which a violent evolution of hydrogen should take place,
is closed with a double-bored rubber stopper similar to
that of a wash bottle. As soon as the solution has as-
sumed a light blue color similar to copper sulphate solution,
the glass tube permitting the free passage of the gas is
closed, so that the hydrogen which continues to develop
vigorously presses the solution out of the flask through
the second tube which reaches to the bottom. It is filtered
through a small bulb-tube with asbestos and then enters
154 LABORATORY MANUAL OF
directly, without coming in contact with air, into a solu-
tion of 500 grams crystallized sodium acetate in 2 litres of
water. The red precipitate is washed by decantation sev-
eral times with water saturated with carbonic acid and pre-
served as a paste.*
KgCr20T+ 14HC1 =2KC1 + 2CrCl3 + 6CI + 7HgO;
2CrCl3 + Zn = 2CrCl2 + ZnCl2 ;
CrClg + 2CH3COONa = 2NaCl + ch8— COO > Cr'
The reduction of the chromium chloride only takes place
rapidly and completely in concentrated hydrochloric acid
solution with large excess of zinc. Chromium monochloride
absorbs the oxygen of the air with great rapidity, while the
insoluble chromium acetate is fairly stable in air.
The red paste should form a blue solution with diluted
HC1, and by energetic absorption of oxygen this quickly
turns dark green.
POTASSIUM CHLOROCHROMATE.
Cr03 < £jK
100 grams potassium dichromate ?re powdered and
gently heated in a flask with a mixture of 100 c. c. of
water and 130 grams pure fuming HCl. As soon as dis-
solved, it is filtered and allowed to settle. Next day the
* Pfordten Annalen, 228, 113.
INORGANIC PREPARATIONS. I 55
crystals are separated from the mother liquor by decanta-
tion and dried on an earthen plate.
KO-CrOo -> n , 9Hn _KO— Cr02Cl+H n
KO— CrOo ^ ° + 2HU ~- KO— CrO.Cr H2°-
The large, red prisms or plates develop chlorine gas on
heating to ioo°C.
SELENIUM.
Se2.
Seleniferous material or residues are melted in a Hes-
sian crucible with a mixture of equal parts soda and salt-
petre. The cooled fusion is boiled up with water, the ex-
tract condensed to small volume, and the solution, which
has been made strongly acid with cone hydrochloric acid,
is boiled with a reversed condenser until no more chlo-
rine gas escapes. Now it is diluted in a large flask with
plenty of hot water, and commercial sodium disulphite
dropped into the boiling liquid as long as a red, very vol-
uminous precipitate, which quickly clots to blackish, ugly
masses, is formed. The separated selenium is settled, col-
lected on a filter and dried.
In fusing with soda and saltpetre seleniferous mate-
rials produce selenates ; selenic acid is quickly reduced
in cone, solution by muriatic acid :
H2Se04 + 2HC1 = H2Se03 -f 2C1 + H20.
Selenious acid is decomposed by sulphurous acid :
H3Se03 + 2H2S03 = Se + 2H2S04 + H20.
The selenium should melt at 2170 C, and when cooled
slowly crystallize in dark-gray, metallic-shining masses ;
I56 LABORATORY MANUAL OF
it should dissolve in cone, sulphuric acid, with a green
color, and be reprecipitated out of this solution by water
as a very voluminous red armorphous deposit. Heated
in the air it should burn to selenium dioxide without re-
sidue, leaving an odor of radishes.
HYDROFLUOSILICIC ACID.
H2SiF6.
100 grams calcium fluoride powder are mixed with
100 grams dry quartz-sand (sea-sand\ and carefully heated
with 350 c. c. cone, sulphuric acid. The escaping gas is
led through an empty bottle containing a safety-tube
closed with a little cone, sulphuric acid, and then into a
porcelain dish, at the bottom of which a small vessel with
mercury has been placed. The gas tube is fastened so
that it dips into the mercury, and then 400 c. c. distilled
water are poured over it. After the gas evolution has
ceased, the silicic acid, which has separated in the water,
is filtered, washed with a little water, until the combined
filtrates amount to 400 c. c, and the still cloudy acid is
filtered through a folded filter.
By the water-absorbing action of the sulphuric acid
there is a formation of silicon fluoride : Si02 + 4HF— 2H20
= SiF4; this gas is decomposed by water : 3SiF4 + 4H30
= 2H2SiF6+Si(OH)4.
The acid should yield a precipitate (Ba2Si04) with
barium chloride, but not with strontium chloride, in hydro-
chloric acid solution. To determine its value, the acid
is titrated with soda solution to alkaline reaction. The
INORGANIC PREPARATIONS. 157
neutralization of the acid on titration with soda corresponds
with the equation : H2SiF6 + 6NaOH = 6NaF -h Si(OH)4 +
2H20.
PERCHLORIC ACID.
HC104.
50 grams potassium perchlorate are distilled out of a
good-sized retort with a mixture of 100 grams cone.
H2S04 and 20 c. c. water. The distillate is freed from chlo-
rine gas by gently warming, a few centigrammes of silver
sulphate and barium carbonate added, the trifling precipi-
tates of each filtered separately, and the filtrate redis-
tilled.
KCIO4 + H2S04= HC104 + HKSO4.
The crude acid still contains traces of HC1 and H2S04,
which are removed in the manner described.
In a solution of potassium chlorate a drop of the acid
produces a thick crystalline precipitate.
MANGANESE.
Mn2.
300 grams crystallized manganous chloride are grad-
ually dried in a porcelain dish on the gas stove,
and the pieces which have formed, powdered in a hot
mortar and dried until the pale pink-colored powder fails
to clot and a sample heated in a test-tube shows no mois •
ture. 75 grams of the anhydrous manganous chloride are
158 LABORATORY MANUAL OF
thoroughly mixed in a warm condition with 150 grams
dry potassium chloride (the latter must first be heated
in a nickel or iron dish until it no longer decrepitates), and
the mixture packed tight in a clay crucible, 12 cm. high
and 7 cm. wide. The crucible is covered and heated in
the furnace. When the crucible has become red-hot and
the contents are soft, 18 grams magnesium in sticks are
thrown in, in pieces of from 3 to 4 grams each, closing the
crucible immediately after adding each piece and waiting
for the faint reaction. The real difficulty is in rapidly
producing the exceedingly high temperature in the fur-
nace required to fuse the manganese that has formed.
This can be accomplished in Roessler's furnace by pro-
viding a very good gas supply and by introducing a
strong oxygen current through the air-openings on the side
of the furnace. (The oxygen is generated directly from a
large retort, with potassium chlorate and a little black
oxide manganese, which is heated a few minutes before
adding the magnesium. The air-openings of the furnace
are closed loosely with strips of asbestos board, through
which the gas-tubes conveying the oxygen pass.) But a
well-built brick, air or blast furnace, with coke fire, is
preferable. The severe heat must last no longer than
half an hour. Upon cooling, if the operation has proved
successful, the manganese will be found as a regulus. If, in
place of this, only a fine black metallic powder be
found which, on exposure to air, changes very readily
into manganese dioxide, then the heat was too low. If,
on the other hand, the metal has solidified in crusts and
granules, which have not combined to a regulus, then the
crucible contents are ground, the light particles quickly
INORGANIC PREPARATIONS. I 59
elutriated with a large quantity of water, then filtered,
quickly washed with alcohol and ether, dried between fil-
tered paper, and the metallic powder so obtained is pre-
served in well-closed bottles.
MnCl3 + Mg = MgCl3 + Mn.
The magnesium chloride volatilizes and reacts with the
water-vapor of the gases of combustion to form hydrogen
chloride and magnesium oxide. During the operation
there is a considerable evolution of hydrochloric acid gas.
Manganese is a brittle, glossy metal, when exposed to
the air, especially in a finely divided and moist condition, is
very easily oxidizable and when excess of diluted HC1 is
poured over a sample, the metal should dissolve clearly
with a vigorous evolution of hydrogen. The solution
prepared hot should show no turbidity with excess of
ammonia, or at most a hardly noticeable one. When am-
monium sulphide is added to this ammoniacal solution, a
precipitate of flesh colored manganese sulphide forms,
which gradually turns green on boiling. The filtrate from
the manganese sulphide mixed with sodium phosphate
gives a precipitate of magnesium phosphate which is never
entirely absent, but in successful working should be very
slight.
MANGANESE CHLORIDE.
MnCl3 + 4H30.
Residues of chlorine produced from black oxide of man-
ganese and HC1 are evaporated to dryness in a porcelain
dish, and the residue heated for a time on the gas stove
with low flame. It is then boiled up with water and tVth
160 LABORATORY MANUAL OF
of the filtrate precipitated with excess of soda solution.
The precipitate is washed with water decanting several
times, then the main quantity is added to the solution and
digested with it, warming until a filtered sample, mixed
with ammonium sulphide, shows a pure flesh-colored pre-
cipitate, which on dissolving in dil. acetic acid leaves no
residue. It is then filtered and evaporated to crystalliza-
tion.
On heating the dry chlorides and boiling with water,
the compounds of the trivalent metals (iron, aluminium)
decompose with formation of insoluble basic salts. Pos-
sibly the rest of the compound is precipitated by the
manganese carbonate
3MnC03 -f Fe3Cl6 + 3H30 = 3MnCl3 + Fe3(OH)6 + 3C03.
The magnanese chloride is tested for the absence of
iron, barium, calcium and magnesium salts.
SOLUBLE MANGANESE OXIDE.
4(Mn03H20),Mn304.
Obtained by acting on potassium permanganate with
sodium thiosulphate, and thoroughly washing the precipi-
tate with water. As soon as all the potassium has been
removed, a brown solution is obtained, from which the oxide
is precipitated on the addition of any salt. The manga-
nese solution can be kept for a long time in sealed tubes,
but if filtered through paper the manganese is completely
precipitated.*
* W. Spring and G. de Boeck, Bull. Soc. Chim., 48, 170.
INORGANIC PREPARATIONS. l6l
MANGA NOUS SULPHIDE.
MnS.
Manganous sulphide is thrown down from ammoniacal
manganous solutions by ammonium sulphide as a pink
precipitate, which the older workers supposed to be a hy-
drated sulphide ; however, it is shown that if it is collected,
washed in an atmosphere of hydrogen sulphide, and dried
at yo° C. in a current of carbonic anhydride it has the
composition MnS. The sulphide thus obtained consists
of tiny, reddish, transparent crystals, and is contaminated
with a little sulphur, which may be extracted by treat-
ment with carbon bisulphide; its sp. gr. at iyQ C. is 3.55.
If the red precipitate i3e well washed, and left in a
solution of ammonium sulphide for a few days, it turns
green ; the same change is also brought about by heating
the red powder at 300 to 3200 C. The green modifica-
tion is crystalline, and has the same composition as the
red, but a somewhat higher sp. gr., namely, 3.63, re-
ferred to water at 17° C. Neither modification loses sul-
phur on heating.*
MANGANESE SULPHATE.
MnS04,5H20.
A concentrated solution of MnS04 is treated with 95
per cent, alcohol, when almost all of the sulphate sepa-
rates out as a syrupy liquid, which after a short time
By U. Antony and P. Domnint, Gazzetta, 23, i., 560-567.
162 LABORATORY MANUAL OF
begins to form crystals. If, at this point, the liquid and
alcohol be repeatedly and strongly shaken, a crystalline
meal results, but if allowed to remain at rest, well-formed,
reddish white, prismatic crystals are deposited.*
POTASSIUM MANGANATE.
K2Mn04.
Potassium hydroxide (2 mols) is placed in a crucible,
some water is added, and finely divided potassium per-
manganate (2 mols) is added, with constant stirring and
heating. After two hours at a faint red heat the crucible
is cooled, and the manganate placed in a well-stoppered
flask, to prevent access of air and contact with organic
matter, t
BARIUM MANGANATE.
BaMn04.
This green pigment is prepared by heating manganese
carbonate with 2 to 2. 5 times its weight of commercial barium
dioxide in a porcelain crucible. A better green is ob-
tained when well-pulverized manganese dioxide (contain-
ing 91 per cent, of MnOg) is heated with three times its
weight of barium dioxide.j:
PREPARATION OF BARIUM PERMANGANATE.
BaMn308.
Potassium permanganate (100 grams) and barium ni-
trate (140 grams) are disolved in water (i*4 litres), and
* B. Classen, Arch. Pharm. [3] 25, 310.
f A. Joller, Rep. Anal. Chem. 1887, No. 33.
X E. Donath, Dingl. Polyt. Jr. 263, 246.
INORGANIC PREPARATIONS. 163
to the boiling solution barium hydroxide is added in por-
tions of 20 grams, until no further evolution of oxygen
takes place. The whole is then warmed 'until the solu-
tion has become colorless, the precipitate of barium man-
ganate (containing also some peroxide and carbonate) is
collected, washed 5 times by decantation with 5 litres of
boiling water, collected on the filter-pump, washed 10
times more with boiling water, suspended in water (1 litre)
and carbonic anhydride, and superheated steam passed into
the mixture for 10 hours. The solution is then filtered
twice through an asbestos filter ; it contains 65 to 80 grams
of barium permanganate.*
FERRIC CHLORIDE.
Fe2Cl6.
Heat small iron nails in a flask with a mixture of 10
parts of water and one part of pure hydrochloric acid until no
further evolution of hydrogen is observed, even after add-
ing the nails in excess; filter the solution into another flask,
and conduct into it chlorine gas, with frequent shaking un-
til the fluid no longer produces a blue precipitate in a solu-
tion of potassium ferricyanide. Heat until the excess of
chlorine is expelled.
Solutions of ferric chloride must not contain an excess of
acid ; this may be readily ascertained by stirring a diluted
sample with a glass rod dipped in ammonia, when the
absence of any excess of acid will be proved by the forma-
tion of a precipitate which shaking the vessel or agitating
the fluid fails to redissolve. Potassium ferricyanide must
not impart a blue color to it.
* By F. Muthmann, Rer. 26, 1016-1018.
164 LABORATORY MANUAL OF
ANHYDROUS FERROUS CHLORIDE.
FeCls.
Into a retort, which has been warmed and fitted up for
the production of ferric chloride, about 20 grams
anhydrous ferric chloride are poured as quickly as
possible. A strong current of carefully dried hydrogen
gas, developed from a Kipp's apparatus, is passed over it.
The retort is placed on a gas stove which may be lighted,
when it is certain that the air has been entirely removed from
the apparatus; the heat should be moderate. Astrong evo-
lution of hydrogen chloride takes place at once ; the gas
is collected in water. . When the chloride in the retort has
changed to a white crystalline mass and the evolution of
HC1 ceases, the operation is concluded. It is then allowed
to cool in a slow current of hydrogen ; the retort is broken
while still warm and the collected chloride preserved in the
same manner as the ferric chloride.
Fe3Cl6 + 2H = 2FeCl2 4- 2HC1.
Anhydrous ferrous chloride forms in white scales, fairly
stable when exposed to air, melting when heated vigorous-
ly and subliming at a very high temperature.
ANHYDROUS FERRIC CHLORIDE.
Fe2Cl6.
50 grams bright iron wire I mm. thick in pieces 6 to 8
mm. long are placed in a tubulated glass retort of ^ litre
capacity and strongly heated on the gas stove, a chlorine cur-
INORGANIC PREPARATIONS. I<?5
rent, dried by two wash bottles with sulphuric acid, is led
into it through a glass tube, which passes through a cork in
the tubulature of the retort ending just above the iron.
The neck of the retort is closed with a bored cork ; the es-
caping chlorine gas is either led out through a rub-
ber tube or else absorbed in flasks by soda or alcohol.
After the operation has lasted I to 2 hours, the gas current
and heat are interrupted, the chlorine which fills the re-
tort is removed by dry carbonic acid, the retort broken
while still hot over a large sheet of smooth paper, and
the ferric chloride separated from the broken glass and un-
changed iron, from which it is very easily removed ; it is
then rapidly placed in dry and warm test tubes prepared in
readiness, tared and fitted with suitable stoppers which are
immediately closed by heating before the blowpipe, taking
care that the aqueous products of combustion do not enter
the tubes.
The ferric chloride formed according to the reaction:
2Fe3-r6Cl=Fe2Cl6 escapes the reducing influence of the iron
on account of its volatility and collects in beautiful crystals
in the upper part of the retort.* The process is only suc-
cessful with complete exclusion of moisture.
Anhydrous ferric chloride forms dark greenish, compact
scaly masses, with a beautiful metallic gloss, dissolving
quickly in brown drops when exposed to the air.
Readily dissolved when vigorously warmed in water,
alcohol and ether; with more difficulty in benzol. The
solutions are colored brown and react acid.
* When the chlorine current is too sluggash there may be a forma-
tion of ferrous chloride, which then remains with the iron as a fused
white mass.
1 66 LABORATORY MANUAL OF
FERROUS SULPHATE.
FeS04,7H20.
Heat an excess of iron nails free from rust, or of clean
iron wire, with dilute sulphuric acid until the evolution of
hydrogen ceases ; filter the sufficiently concentrated solu-
tion, add a few drops of dilute sulphuric acid to the filtrate
and allow it to cool. Wash the crystals with water very
slightly acidulated with sulphuric acid, dry, and keep for
use.
The crystals of ferrous sulphate must have a fine pale
green color. Crystals that have been more or less oxidized
by the action of the air and give a brownish-yellow solution
when mixed with water, leaving undissolved ferric sulphate
behind, may be treated as above, with sulphuric acid and
excess of clean iron wire or nails, until the residue dissolves
and the solution is clear pale green. Hydrogen sulphide
must not precipitate solution of ferrous sulphate after ad-
dition of some hydrochloric acid, nor even impart a black-
ish tint to it
ANHYDROUS FERROUS BROMIDE.
FeBr3.
IOO grams of bright iron wire are vigorously heated in a
round bottom flask on the gas stove, and IOO c. c. bromine
distilled slowly from a water-bath into the flask. The glass
tube conducting the bromine-vapors should reach close
to the bottom of the flask, but the hot glass must be
protected from fracture by the dropping bromine,
INORGANIC PREPARATIONS. 167
either with iron filings or a little asbestos. When the reac-
tion begins the temperature may be somewhat moderated.
Finally dry air or carbonic acid is passed through the
apparatus ; upon breaking the flask the preparation is
gathered and preserved in the same manner as described
for ferric chloride.
IRON AMMONIUM ALUM.
Fe(NH4) (S04)2 f- 12Aq.
400 grams ferrous sulphate are dissolved in 400 c. c. water
70 grams cone, sulphuric acid and about 120 grams of cone,
nitric acid added to the boiling solution until a diluted
sample mixed with ammonia shows a pure rust-colored pre-
cipitate. Now it is evaporated until the mass is resinous
then again diluted with water to sp. gr. 1.3 17 to 1.3 19. To
300 grams of this ferric sulphate solution a solution of 28
grams ammonium sulphate in 100 c. c. water is added and al-
lowed to cool slowly and quietly. The crystals are washed
with a little cold water and dried without warming.
The last traces of nitric acid are removed from the fer-
ric sulphate solution by evaporation.
Iron alum crystals are amethyst-colored octahedra
which must be entirely free from chlorine. Determine the
iron value by weighing the ferric oxide which remains after
ignition with a little ammonium nitrate.
BERLIN BLUE.
Hydrocyanic acid residues (page 124) are washed with
water by decantation and rinsed in a porcelain dish with
1 68 LABORATORY MANUAL OF
crude hydrochloric acid. A chloride of lime emulsion
is prepared by suspending chloride of lime in water, allow
it to flow in, stirring well, through a funnel, the stem of
which rests on the bottom of the dish in the hydrochloric
acid, until the mass has turned to a nice blue color and the
solution begins to smell of chlorine. The precipitate is
washed with a dilute solution of common salt, as it does
not settle in water.
The hydrocyanic acid residues consist of the ferro-salt
of hydrogen ferrocyanide, which is converted into ferric
salt by the oxidizing influence of the " chloride of lime."
PURE PLATINUM.
Pt3.
r- The following method of Finkener's for obtaining plati-
num free from impurities, especially iridium, is here describ-
ed; it depends on recrystallization of sodium platinochloride.
Commercially purified platinum is dissolved in aqua regia, to
the solution of the chloride, freed from oxides of nitrogen,
the calculated amount of pure sodium chloride is added, the
solution is concentrated to a small bulk, and allowed to cool
whilst being continuously stirred. The crystals which sep-
arate are freed from mother liquor by suction, washed with
a concentrated solution of sodium chloride, and dissolved
in a one per cent, solution of sodium carbonate. The solution
is allowed to cool, when the salt again separates. It is
then dried at 1200 C, reduced in a current of hydrogen at a
low temperature, and the platinum sponge thus obtained is
washed for a long time with water, and finally dried and
ignited. The metal thus obtained is extremely pure ; no
INORGANIC PREPARATIONS. 1 69
impurities could be detected in it by the methods mentioned
above and it is calculated that it contains at least 99.99 per
cent, of platinum.*
It may be of interest to mention that pure platinum is
now prepared in Germany. The method of purification is
simpler than the English one, not involving the use of lead,
and it yields a very pure product. In a sample of 40 grams,
no palladium or rhodium could be detected, and only a
trace of iridium; a trace of iron, at most O.OOI per cent.,
was, however, present.
PLATINIC CHLORIDE.
PtCl4, Crystallized -\-lOYi20.
Heat in a clay crucible 5 parts of zinc to fusion, with
sufficient common salt to cover the surface and prevent its
oxidation, then introduce 1 part of platinum scraps in small
quantities at a time into the fused metal. An alloy is
formed from which the zinc is to be removed by digesting
in somewhat dilute common hydrochloric acid, until all
effervescence ceases, and subsequent boiling for a time with
fresh hydrochloric acid. The residual platinum is com-
pletely washed with water and boiled with nitric acid. It
is again washed, and finally dissolved by warming with con-
centrated hydrochloric acid and some nitric acid. Evapo-
rate the solution on the water bath, with addition of hydro-
chloric acid, and dissolve the semifluid residue in 10 parts
of water for use.
F. Myliers & Foerster, Ber. 25, 665.
170 LABORATORY MANUAL OF
Platinic chloride must, upon evaporation to dryness in
the water-bath, leave a residue which dissolves completely
in alcohol.
PLATINIC CHLORIDE.
From Residues.
If the platinum residues contain alkalies and organic
substances they are roasted in a porcelain dish on the gas
stove, then mixed with a little diluted crude hydrochloric
acid and reduced by zinc. The undissolved zinc is removed;
washed and the impure metal boiled up several times with
water and hydrochloric acid. The residue is then dissolved
in aqua regia, evaporated to a small volume and precipita-
ted with cone, salammoniac solution. The filtered platinum
ammonium chloride is ignited in a porcelain crucible, the
residue of spongy platinum boiled with HC1, dissolved in
aqua regia, and evaporated to dryness on the water-bath in
a weighed dish occasionally adding a few drops of HC1.
The residue of pure platinum chloride is dissolved in 10
parts of water.
Ten drops of the solution with one drop of sodium chlor-
ide solution evaporated on a watch-glass to a very small
volume, should on cooling yield a crystalline mass, in
which, under the microscope, only well formed, reddish-yel-
low prisms of sodium platinum chloride are to be seen, and
which must not be contaminated with amorphous, brown
masses (iron ; nitrogen oxide compounds of the platinum
chloride).
INORGANIC PREPARATIONS. 171
• PLATINOSOCHLORIDES.
When potassium platinochloride (12 grams) is heated in
a covered vessel, on a water-bath, with hydrogen potassium
sulphite (9 grams) and water (160 c. c.) for 10 to 12 hours,
the reduction is complete, and the red salt crystallizes out
on evaporation. Similar results are obtained by heating
the platinochloride (9 grams) with potassium hypophosphite
(1 gram) and water (300 c. a), at 80 to 90° C, for 18 to 20
hours. The completion of the action is shown by the pure
ruby color of the solution, the least shade of orange indica-
ting the presence of platinochloride. The first method is
the safest, as the reduction cannot go beyond the platino-
sochloride, but in the second method the red salt separates
more easily and completely, and with care, very good re-
sults are obtained. If, when reducing with potassium hy-
pophosphite, the action is continued after complete
conversion into the red salt, the solution rapidly changes to
dark brown. Hydrochloric acid has no effect on this so-
lution, nitric acid discolorizes it, potash causes a brown pre-
cipitate soluble in excess of the precipitant, and ammonia a
brown precipitate insoluble in excess.*
SPECIALLY ACTIVE PLATINUM-BLACK.
Very active platinum-black can be conveniently pre-
pared as follows: — An aqueous solution (50 to 60 c. c.) of
platinic chloride (50 grams) is mixed with 40 to 45 per
cent, of formaldehyde solution (70 c. a), the mixture cooled
M. Cary Lea, Amer. Jr. Sci., 1894 [3]. 48,397.
1^2 LABORATORY MANUAL OF
well, and then sodium hydroxide (50 grams) dissolved in
water (50 grams) gradually added; after standing for 12
hours the solution is filtered. A yellow liquid, from which
a small quantity of platinum is deposited on boiling, first
passes through the filter, but as soon as most of the salts
have been washed out of the residue, the filtrate assumes a
deep black color. The process is interrupted at this stage
for several hours because the residue soon absorbs oxygen,
the temperature rising to 36 to 40° C, and the washings then
pass through colorless. As soon as oxidation is complete,
the residue is washed until completely free from sodium
chloride, pressed, and dried over sulphuric acid.
If the deep black filtrate referred to above is submitted
to dialysis in absence of air, a black, transparent liquid is
obtained which is stable in absence of air; on exposure to
the air, however, this liquid gradually becomes colorless,
and a small quantity of a black powder is deposited. The
black solution decomposes hydrogen peroxide very energet-
ically, and when mixed with alcohol or shaken with air, the
odor of aldehyde is immediately perceptible. These and
other experiments seem to show that this black liquid is
a solution of atomic platinum containing small quantities of
organic platinum compounds.* -
PENTATHIONIC ACID.
When 10 c. c. of decinormal sodium thiosulphate solu-
tion are treated with a drop of a solution of potassium
arsenite containing 1 per cent, of arsenic trioxide, and
* A. Loew, Ber., 23, 289.
INORGANIC PREPARATIONS. 1 73
with an excess of hydrochloric acid, the solution becomes
turbid and has a slight odor of hydrogen sulphide ; after a
long time arsenic sulphide and a little sulphur are precipi-
tated. When filtered, the solution gives reactions for pen-
tathionic acid.*
PREPARATION OF CRYSTALLIZED HYDROXY-
LAMINE.
A mixture of dry hydroxylamine zinc chloride (10
grams) and anhydrous aniline (20 c. c.) is distilled under
a pressure of 20 m.m. on a water-bath. The distillate of
hydroxylamine, which crystallizes on cooling, is washed
with ether, care being taken to prevent access of moist air;
or dry ammonia gas is passed through absolute ether, hold-
ing the zinc salt in suspension, and the decanted etherial
solution of hydroxylamine is subsequently distilled under
reduced pressure, when crystals are obtained. f
HYDROXYLAMINE HYDROCHLORIDE.
A saturated solution of sodium nitrite (1 mol.) is
added to a solution of hydrogen sodium sulphite (2
mols.) in a cooled vessel, and then a cold saturated solution
of potassium chloride is added. In 24 hours hydroxyla-
mine potassium disulphonate separates. This salt is boiled
in water during several hours, and, on cooling, potassium
sulphate is first deposited, and subsequently hydroxyla-
* T. Salzer, Ber. 19, 1696.
f L. Crisner, Bull. Soc. Chim. [3], 6, 793.
174 LABORATORY MANUAL OF
mine sulphate. A solution of this salt, treated with the
necessary amount of barium chloride, yields the hydro-
chloride, which can be obtained in colorless crystals, very
hydroscopic, easily soluble in water and alcohol. It melts
at 15 1° C, and decomposes at a higher temperature,
yielding nitrogen, hydrogen chloride, ammonium chloride,
and water.*
HYDRAZINE.
Hydrazine sulphate is best obtained when triazoacetic
acid (250 grams in 2 litres of water) is warmed with sul-
phuric acid (300 grams) until all effervescence ceases; the
sulphate crystallizes out on cooling. More may be ex-
tracted from the mother liquor by shaking with small
quantities of benzaldehyde, thus converting the hydrazine
into benzalazine, which separates out ; after recrystalliza-
tion this is decomposed by sulphuric acid, whereby hydra-
zine sulphate and benzaldehyde are formed ; the latter is
then distilled off.t
CHYDRAZAINE OR PROTOXIDE OF
AMMONIA.
Chydrazai'ne is evolved when a solution of possium per-
manganate (158 grams) and sulphuric acid (40 grams S03) is
slowly added to dried, crystallized ammonium oxalate(i4i.2
grams) the whole well mixed and gently heated until it begins
* Eichkoff, Arch. Pharm. [3], 27, 713.
f T.CuRTiusand R. Jay, Jr. pr. Chem. [2], 39, 27.
INORGANIC PREPARATIONS. I 75
to boil. The gaseous product is absorbed in hydrochloric
acid, and a neutral solution of the salt can thus be obtained.
The hydrochloride is crystalline, and very readily soluble
in water, but only sparingly in alcohol. The sublimed
salt has the composition N2H6022HC1, but the crystals
dried by means of the anhydrous salt contain one-fifteenth
of their weight of water. When a solution of the hydro-
chloride is mixed with platinic chloride, a platinochloride
is obtained, the composition of which varies with the con-
ditions of the experiment ; with excess of the hydro-
chloride a yellow salt is formed, the composition of which is
approximately N2H60,H3PtCl6,but if excess of platinic chlo-
ride is added the proportion of platinum is sensibly increased.
The sulphate is crystalline and soluble in water, but only
sparingly so in absolute alcohol ; it forms a double-salt
with aluminium sulphate. The nitrate is crystalline When
a solution of the nitrate is evaporated, nitric acid, nitric
peroxide, nitrogen, and a compound having the composi-
tion N2H2 are evolved.*
CARBON OXYSULPHIDE
COS.
Is prepared by adding 50 c. c. of a concentrated aque-
ous solution of potassium or ammonium thiocyanate to a
cooled mixture of 290 c. c. (520 grams) of strong sul-
phuric acid and 400 c. c. of water. The whole is heated
at 25 ° C. in a water bath. The gas thus prepared con-
tains only about 2.5 per cent, of carbonic anhydride and
O.05 per cent, of carbon disulphide. The latter is absorbed
* E. J. Maumene, Bull. Soc. Chim. 49, 850.
I*j6 LABORATORY MANUAL OF
by passing the gas through triethylphosphine and this in
turn is removed by pure sulphuric acid. Carbon oxysul-
phide is only absorbed very slowly by a 33 percent, solu-
tion of potash. If the gas obtained as above is passed
slowly through about 20 c. c. of such a solution, the whole
of the carbonic anhydride is absorbed with a loss of only
about 7 per cent, of the oxysulphide. A 33 per cent,
aqueous solution of potash mixed with its own volume of
alcohol absorbs carbon oxysulphide completely and rapidly,
and is the best reagent for use in estimating it.
Pure carbon oxysulphide is odorless and tasteless. Its
physiological effects are very similar to those of nitrous
oxide. When passed through a saturated solution of
baryta, no opalescence is produced for at least half a min-
ute, while if any carbonic anhydride is present, the solu-
tion becomes milky at once. With lead acetate solution,
the precipitate is a quarter of an hour in forming.*
NEW METHOD OF PREPARING CARBON OXYSULPHIDE.
Carbon oxysulphide is obtained when carbonyl chloride
is passed through concentrated sulphuric acid to dry it,
and then through a tube 50 cm. long, filled with ignited
asbestos well mixed with finely pulverized cadmium sul-
phide, the tube being placed in a combustion furnace and
heated. Even when no external heat is applied a small
quantity of carbonyl sulphide is formed, but the most
favorable temperature for its formation appears to be 260 to
2800 C. The gas thus produced is found on analysis to
contain COS, 94.87 per cent ; CO, 3.98 per cent.; air 1.15
per cent. A quantity of crystals, which are identified as
* P. Klason, Jr. pr. Chem. [2], 36, 64.
INORGANIC PREPARATIONS. I 77
cadmium chloride, are observed in a tube previously
charged with a layer of cadmium sulphide and heated in a
flame during the passage of a current of carbonyl chloride ;
the reaction, therefore, appears to be a double decompo-
sition.*
PURIFICATION OF CARBON DISULPHIDE.
To one litre of carbon disulphide 0.5 c. c. bromine is
added and allowed to remain for 3 to 4 hours. The bromine
is then separated again by shaking the carbon disulphide
with a slight excess of potash or by means of copper turn-
ings. The carbon disulphide may now be opalescent, but
this is readily removed by agitating it with a little potas-
sium chloride, when the filtered disulphide will be obtained
clear, colorless and of agreeable odor. It leaves no resi-
due on evaporation.!
* By J. Nuricsan, Ber. 24, 2967-2974.
•f A. Chenevier, L'Union pharm., 33, 204.
178 LABORATORY MANUAL OF
VOLUMETRIC ANALYSIS.
The methods in use are based on the fact that equiva-
lent weights of various substances will mutually react.
Simple cases of this kind are found in the neutralizing
of acid by alkaline solutions or vice versa. For instance ;
suppose we have a solution of potassium hydroxide,
which shall contain 56.1 grams of solid KOH per liter,
this will be equivalent to a solution of hydrochloric acid
containing 36.5 grms in the same volume and any equal
fractional parts of these solutions will exactly neutralize
each other.
In this case we have used the molecular weights as
units, since both acid and alkali are monobasic. Hence
whenever the acid and alkali are monobasic, we should use
the molecular weights or some equal fractional parts of
these weights, as J^, i/5, y10, &c.
In this class will be included such common alkalies as,
sodium and ammonium hydroxides and acids like nitric
or acetic.
The general type reaction may be expressed as
follows :
KOH + HC1 = KC1 + H20
56.1 + 36.5 - 74-6+ 18
A somewhat modified statement must be made when
the alkaline and acid substance are dibasic, such is the
case, with sodium carbonate and sulphuric acid both of
which are dibasic. Writing the equation we find that:
Na2C03 + H2SO4 = Na2S04 + H20 4- C02
106 + 98 = 142 + 18 +44
substituting HC1 for H0SO4, that is, two units of the
INORGANIC PREPARATIONS. I 79
former are required to do the work of one of the latter
acids, hence t'o bring the sodium carbonate solution to an
equality with the hydrochloric acid, we must use 53
grams or one- half the molecular weight and 49 grams of
sulphuric acid.
In the few cases of tribasic substances we use one-
third of the molecular weight. All these solutions are
called Normal, and in their preparation, it is found con-
venient to start with sodium carbonate, which can be ob-
tained pure and dry with little difficulty, 53 grams of this
substance are carefully weighed out and dissolved in some-
what less than one liter of water, when. in perfect solution,
the liquid is cooled to about 150 C and diluted to exactly
one liter, this forms an accurate Normal solution of alkali
by means of which, we can prepare the acid solution.
Suppose sulphuric acid is chosen, it will be found
difficult to weigh out liquids and much easier to calculate
their volume from the Specific Gravity and required weight
as follows: Pure sulphuric acid has a Sp. Gr. of 1.84 at
1 5° C and the required weight is 49 grms, hence if we
divide 49 by 1.84 we shall have the volume occupied by
the acid, this will be found to be 26 -|- c.c., now taking
27 c.c. of acid and carefully pouring it into somewhat less
than one liter of water, we cool the solution and dilute to
one liter. The acid is too strong, having being made so
purposely, and it is now necessary to obtain data for
making it exact. For this purpose we introduce some of
the solution into^a rjtarette and having taken say 10 c.c. of
the sodium carbonate and added water about 100 c.c. and
a few drops of some coloring matter to act as an indicator
(for this case we will use methyl orange, pink when acid,
l8o LABORATORY MANUAL OF
yellow when alkaline). The acid is slowly run in from the
burette with constant stirring until the liquid just reacts
acid, 9.8 c.c. have been used, consequently every 9.8 c.c.
contains as much acid as should be held by 10 c.c. of the
solution and hence every 9.8 c.c. should be diluted to 10
c.c. To make the solution correct, we should then take
980 c.c. of the original and dilute to exactly one liter. A
confirmatory test is usually made on the corrected solution.
Such solutions keep very well, it merely being neces-
sary to guard against evaporation. The alkalies, made up
in similar manner, must also be protected from carbon di-
oxide, sulphur dioxide, hydrogen sulphide, &c.
The most commonly used indicators are solutions, of
phenolphthalein in 50% alcohol, acid colorless, alkaline
pink to violet ; good for all acids organic and inorganic
and all alkalies except ammonia, but acid to carbon dioxide
and hence useless for carbonates, and methyl orange
aqueous solution, pink when acid, neutral salmon tint and
yellow when alkaline, good for inorganic acids and all
alkalies.
To test an unknown liquid, first find by qualitative
method its character, acid or alkaline, and then which par-
ticular acid or alkali, when these facts have been established
determining the quantity as follows ; we may assume that
the liquid contains Na OH, take 10 c.c, dilute carefully to
100 c.c. and then take 10 c.c. of this solution correspond-
ing to 1 c.c. of the original, add the required amount of
indicator and then run in acid cautiously until the neutral
point is reached, repeat the experiment and if the two do
not differ by more than one-tenth of a c.c. take the aver-
age. The number of c.c. of acid used multiplied by 100
INORGANIC PREPARATIONS. l8l
will give the per cent, of purity, providing- no other re-
acting substance is present.
If in the dry form, weigh out some aliquot part of the
normal weight, dissolve in water, cool and dilute to normal
bulk and titrate as before. For instance suppose the sub-
stance was sodium carbonate Na2C03 molecular equivalent
53, weigh out 5.3 grams, dissolve in water, make up to
100 c.c. and titrate.
DETERMINATION OF SOLUBLE CHLORIDES.
Make a tenth normal solution of silver nitrate, by
weighing out exactly 17 grams of pure dry salt and dis-
solving same in cold distilled water, when in solution dilute
to exactly one liter.
This solution may be used in determining the chlorides
in drinking water.
The type reaction is as follows r
NaCl + AgN03 = AgCl + NaN03
58.5 170 142.5 86
The chloride present is assumed to be sodium chloride
but is not necessarily so.
Take 100 c.c. of the water equivalent to 100 grams or
IOOOOO milligrams, place in a shallow porcelain dish or
casserole and add two drops of a saturated solution of po-
tassium chromate which acts as an indicator, now cau-
tiously run in the silver nitrate drop by drop from a
burette, stirring after each addition and stopping at the
first appearance of a salmon pink color. Read off the
1 82 LABORATORY MANUAL OF
number of c.c. used and multiply by 5.85 the number of
milligrams of NaCl corresponding to 1 c.c. of the AgNOs,
this will give the number of parts in 100000.
SOLUTION OF POTASSIUM DICHROMATE.
In this operation the conditions are so'mewhat different
from the preceding case, notably in the fact that the oxi-
dizing power of the reacting substance is measured in terms
of some standard usually a soluble ferrous salt.
The reaction for the change is expressed by the follow-
ing equation :
K2Cr207 + 14HCI + 6FeCl2 = 3Fe2Cl6 +
2KCI + Cr2Cl6 + 7H20
from which it is obvious that one equivalent of the dibasic
salt K2Cr20y is equal to six parts of iron, hence the normal
strength is usually y60, 1 c.c. of which is equal to 0.0056
grams Fe and called N/10.
Potassium dichromate may readily be obtained pure
and keeps well in solution. Dissolve 4.9 grms (eV of the
molecular weight) in distilled water and make up to one
liter.
Dissolve 100 milligrams pure iron wire in 20 c.c. of
HC1 cone, and an equal volume of water, when in solution
add hot SnCl2 solution, drop by drop, until all color disap-
pears, then add an equal bulk (100 c.c.) of boiled distilled
water and all at once 5 to 10 c.c. of mercuric chloride solu-
tion, this should cause a white silky precipitate of mercur-
INORGANIC PREPARATIONS. 1 83
ous chloride,- if gray or black, reject and start over again
using less SnCl2,
Now run in the dichromate slowly from a burette, test-
ing small portions from time to time, with drops of the in-
dicator KtfFe2 (CN)i2 on a porcelain plate ; the spots will
first be blue; when this diappears and is replaced by a
brown color, stop the titration and note the number of
cubic centimeters used, multiply by 0.0056 for the weight
of iron present. This solution is also indirectly used for
the determination of glycerine and for various other sub-
stances.
When applied to the determination of iodine some
slight modification of the process is necessary. The
equation for the change is as follows :
6KI + K2Qr207 + 7H2SO4 - 3I2 +
4K2SO4 + Cr2 (S04)3 + 7H2O
To any convenient quantity of the iodine solution add
dilute sulphuric acid and sufficient dichromate to free all
the combined iodine ; the liquid should be cold to prevent
loss of the halogen. Now determine the liberated iodine
by titrating with lN7io sodium thiosulphate reacting as
follows :
2Na2S203 + I2 = 2NaI + Na2S406
Thin starch paste is used as an indicator, and as long as
any free iodine is present the solution remains blue.
The estimation is more accurate, if chloroform or car-
bon disulphide be used as solvents for the iodine. The
operation is conducted in a glass stoppered flask.
The N/io solution of Na2S203 contains 24.8 grams of
the crystalized salt per liter.
1 84 ' LABORATORY MANUAL OF
SOLUTION OF POTASSIUM PERMANGANATE.
Potassium permanganate has a greater oxidizing power
than dichromate and will act in acid and alkaline solutions
although the former is preferred and more extensively used;
it has the further advantage of serving as an indicator by the
disappearance of its characteristic color. Although used
extensively in quantitative analysis for the determination
of iron, the example furnished will be its reaction with
oxalic acid according to the following equation :
5H2C2O4, 2H2O + 3H2SO4 + K2Mn208 = 10CO2 +
18H2O + 2M11SO4 +K2SO4
from which it is obvious that 316 parts of permanganate
will oxidize 450 parts of H2C2O4. The usual strength of
the solution is 3.16 grams per liter called 50th normal.
The titration should be carried on at a temperature of
about 8o° C.
Calcium may be determined in this manner, but it is
first necessary to precipitate the metal in the form of oxal-
ate and then decompose this salt with excess of warm dilute
sulphuric acid, the oxalic acid formed in this reaction is
then determined with permanganate.
SOLUTION OF POTASSIUM CYANIDE.
This solution is largely used in the determination of
copper. The reaction proceeds according to the following
equation :
CuS04 + 4KCN ,== K2Cu(CN)4 + K2SO4
hence 260 parts of KCN react with 63 parts of copper.
INORGANIC PREPARATIONS I 85
The solution most frequently used is approximately %
Normal, but in any case the exact strength must be deter-
mined by titration with a known solution of pure copper.
For this purpose dissolve 1 gram of pure copper foil
in strong nitric acid Sp. Gr. 1.2 with the aid of heat, when
the copper has dissolved, boil to expel the oxides of nitro-
gen and excess of acid, cool and dilute to 200 c.c, 1 c.c. of
this liquid will contain 5 milligrams of copper. Take
10 c.c. of this liquid, make alkaline with ammonium hy-
droxide and then add 3 or 4 c.c. in excess, the precipitate
which first appears will dissolve and a clear deep blue
liquid will result, now dilute to about 100 c.c. and run in
the cyanide solution from a burette, with constant stirring
until the color fades away and is replaced by a delicate
pink tint. Divide the number of milligrams of copper
used (50) by the number of c.c.'s of cyanide solution used,
the result will be the value of each cubic centimeter in
copper.
Analyses are made in similar manner.
Table of the Chemical Elements with their Atoiic Weights
Compiled by F. W. Clark
And Reported to the American Chemical Society.
ATOMIC
ELEMENT SYMBOL WEIGHT
Aluminum Al 27.1
Antimony. Sb 120.4
Argon A 40.0(?)
Arsenic As 75.0
Barium Ba 137.4
Bismuth Hi 208.1
Boron B 11.0
Bromin Br 79.95
Cadmium Cd 112.4
Caesium Cs 132.9
Calcium Ca 40.0
Carbon C 12.0
Cerium Ce 139.4
Chlorin CI 35.45
Chromium Cr 52.1
Cobalt Co 59.0
Columbium Cb 93.7
Copper Cu 63. 6
Erbium Er 166.3
Fluorin F 19.0
Gadolinium Gd 156.8
Gallium Ga 69.9
Germanium Ge 72.5
Glucinum Gl 9.1
Gold Au 197.2
Helium He 4.0(?)
Hydrogen 11 1.008
Indium In 113.8
Iodin 1 126.85
Iridium Ir 193.1
Iron. Fe 56.0
Lanthanum La 138.6
Lead Pb 206.9
Lithium Li 7.03
Magnesium. ... .Mg 24.3
Manganese Mn 55.0
Mercury Hg 200.0
(186)
ATOMIC
ELEMENT SYMBOL WEIGHT
Molybdenum . . Mo 96.0
Neodymium .... Nd 143.6
Nickel Ni 58^7
Nitrogen N 14.04
Osmium Os 191.0
Oxygen O 16.0
Palladium Pd 105.4
Phosphorus. ...P 31.0
Platinum Pt 194.9
Potassium K 39.11
Praseodymium . . Pr 140.5
Rhodium Rh 103.0
Rubidium Rb 85.4
Ruthenium Ru 101.7
Samarium Sm 150.3
Scandium Sc 44.1
Selenium Se 79.2
Silicon Si 28.4
Silver Ag 107.92
Sodium Na 23.05
Strontium Sr 87.6
Sulfur S 32.07
Tantalum Ta 182.8
Tellurium Te 127.5
Terbium Tb 160.0
Thallium Tl 204.1
Thorium Th. 232.6
Thulium Tm 170.7
Tin Sn. H9.0
Titanium Ti 48.1
Tungsten W 184.8
Uranium U. 239.6
Vanadium V 51.4
Ytterbium Yb 173.2
Yttrium Yt 89.0
Zinc Zn 65.5
Zirconium Zr 90.4
<
u
X
m
I
<
O
PS
o
<
E-
CO
'5 3 2
Sulphuric Acid.
»
Sp.O,
si?
it
'""C'f,
I*'
H,SO,
Standards Adopted.
°
I.oo7
62.37
62.81
°:Z
°:»3
°i
o-935
Bgaume' Hydrometer.
1.014
63.24
2.50
1.58
3
2-337
63.68
3.66
2-33
Modulus, = 145
5
1.028
64.12
64.62
5-oo
6.0a
3-88
54
7
4-675
5.6.0
66th degree = Sp. Gr. 1.835
1.043
65.05
7.00
4-55
Si
6-545
at Standard Temp. 60° Fr.
7
l.oS.
65-55
5-24
"*
7.480
8.4.5
1 .058
65-99
9.00
5-94
9
1.066
6.82
13
9-584
66.99
11.50
7.70
'5,
■0.752
1 cu. ft. Water, = 62.37 lb3- Av-
1.082
67.48
12.50
16*
11.687
67.98
9-25
18
12.716
'3
..098
1. 107
68.48
69.04
'it'll
10.07
11.05
«9*
'3-744
.4.960
H,SO, = 100
■5
1.115
69.54
11.82
23
■5-895
H,SO, O. V. 60
16
>7
1 -'33
70.67
.8.25
'9.60
'2-79.
■3-85
25
26J
17.064
18.326
O. V. 93.50 100 120.48
21. OO
.4.96
284
■9-635
6o° 77-6os S3 100
•9
1.151
71.79
■5-79
3°
20.570
1. 160
72-35
23-25
32
21-739
50° 62.18 66.5 80.12
11
..169
■•■79
72.91
73-53
24-5°
19'.I2
H
24.310
23
1.188
74.10
28!5o
37i
25-479
26.647
AUTHORITIES —
1.198
74-72
394
75-34
4.4
28.050
Bineau, Kolb, H. Pemberton,
26
75-97
3'-25
23-74
434 29
Gmelin-Krout, J. P. Putnam.
27
1.229
76.65
3= -7 5
25.10
46
77.28
26.28
3'-79o
29 i.aso
77.96
35-5°
37.00
27.68
29.10
50
52
33-'9J
34-595
E. D. Pearce, Jr.,
79-33
38.37
30.44
544
35-876
Nicholas Lennio,
32 \ '-'»3
80.02
39-75
3'.8.
56j
37.166
Henry Bower,
33
■-29S
80.77
41-25
33-32
§9
38.569
39-8SO
34
81.46
34-72
6.
36
37
1. 3 18
82.20
44.00
36-.?
63i
41.140
''■11°
82.95
83.70
45-5°
47.00
37-74
39-34
68J
42-542
43-945
Per Ccnl.
1- j.
Per Ccl
p.,„i.
3«
'■355
84.5,
85-32
48.50
50.00
IU
45-347
46.750
60"
■ "■■«■
s«» '
in ,Scu. ft.
40
..38.
86.13 51.50
44-36
76
48.152
62.05
S3 44
77-44
66.70
■■394
86.94
53-oo
46.08
49-555
63-8S
55
5'
79.70
69.29
1.408
87.82
54-5o
47.86
50-9S7
65.66
S7
66
81.95
88.63
56.00
49-63
84
52.360
67.47
59
84.21
74.64
44
,.436
89.56
57-5 =
5"-5o
87
53-762
69.28
62
05
86.47
45
1.450
90.44
":°o
53-36
90
55-'6s
7I.08
64
46
1.465
9"-37
55-28
93
56.567
72.89
66
60
90.98
S3-.3
92.25
62.00
57-2o
96
S7-97o
74-70
68
9'
93-23
86.00
48
'■495
93-24
63.50
8£
99
59-372
76.50
95-49
89.03
1.510
94.1S
65.00
60.775
78.3"
Jo
7S
97-74
92.05
95.18
95.18
63.29
■05
62.177
5'
■•542
96.17
65.40
1084
63.580
8. -93
78
79
102^6
98-34
5' '-5S9
97-23
69.70
67.77
65.169
66.665
83-98
8.
65
104.81
! S3 ! '.576
98.30
71.30
70.09
85-90
84
107.22
105.40
54 1 '-593
99-36
73.00
72-53
..84
68.255
87.9S
87
109.77
109.07
55 »•*«
,00.48
; 1. 60
74.96
69.7S.
89.S8
3'
112.18
112.72
101.60
;6.ao
77-42
.26
7L247
91.8.
93
1.4.59
116.42
s2
,....,«
102.79
77.87
80.04
u9j
72.S08
93.82
96
.20.37
58
i.i.i 1,
103.91
79.50
82.61
95-78
99
52 '.9.55 ! 124.22
1.686
-5 Jj
jU-o"
85-50
■37
76:0,5
97-95 ' .03
, 10C
B3.00
77. 605
,.;.-.,
107.65
9 '50
'45
79-47S
24' 127. 82 137.60
61
1 :r
10S.96
87.0a
94.80
■491
■S3i
8" .345
.04:82 1,4
21 130.S3
'42.55
...
, 768
110.27
,8.. 4
5,- ;.
'=7.23
-1
■33-83
'47-57
'■4
1
1.790
11. .64
91.62
.02.29
'58
85.665
110.39
'23
24
'37-77
■53-81
1
93-'2
.04.60
;«°*
87.067
,
112.70
.05.94
S7.S90
I
94.70
107.02
,614
88-S44
12S.94
.42.41
1.S1.S
"3-39
95.66
.08.47
:64l
89.442
j
1 814
,,,7,,
-)6 So
90-508
(J
.66
91.939
M4-4S
IOO.OO
"4-45
■«j
93.500
.20.48 .37.S9
150.3S .72.. 1
ALLOWANCE FDR TEMPERATURE.
Approximate Boiling Points
Al 10" B6 46° Fr. _ 1° Be.
Add. Fr. Acid. Fr.
30.15 « - ■• ■•
50= 2,, , 63* 42 |
31.46" = •■ -
6o° 378 1 64° 446
50° " 34-69" = '
6"° 388 65= 473 ;
6a° 403 66 ' ;.•:
66° » 43-14" - » «
!
INDEX.
PAGE.
Acid , Arsenic '. 1 3 5
Bismuthic 142
Boracic no
Dithionic 99
Hydriodic 122
Hydrobromic 1 iS
Hydrochloric 15, 16
Properties of, 16
Hydrocyanic 124
Hydrofluoric 125
Hydrofluosilicic 156
Hydrosulphuric 25
Nitric 17
Properties of 19
Perchloric 157
Pentathionic 172
Phosphoric 129
Silicic, Crystalline 113
Sulphuric 22
Sulphuric, Normal Solu-
tion of 179, 180
Sulphuric Properties of . . 24
Alcohol, Commercial 5
Ethyl 5
Aluminium Chloride 114, 115
Anhydrous, 117
Hydrate 115
Oxide, reduction of, 116
Alum, Iron Ammonium 167
Ammonia .16, 30
" Hydrate 30
Ammonium Bicarbonate ...... 67
Bromide .-...■ 68
Chloride 55
' ' Properties
of 56
Hichromate 70
Di Hydrogen Phos-
phite 72
Molybdate 54
Nitrite 71
Oxalate 43
Properties of, 44
Persulphate 69
Protoxide 174
Sulphide 41
Properties
of 43
Ammonio Zinc Chlorides 72
PAGE.
Antimony Oxychloride 138
" Sulphate 143
" Trichloride 137
Antimonious " 139
Arsenic Pentasulphide 137
" Trioxide 22
Atomic Weights 186
Auric Chloride 83
Auroso Auric Chloride 84
Barium Carbonate 98
" Chloride 96
" Dithionate . 99
" Hydroxide.. 35
" Manganate 162
" Nitrate . . 97
" Oxide 95
' ' Perhydrate- 98
" Permanganate 162
" Peroxide . 98
Baryta Water 35
Berlin Blue . . . 167
Bismuth Hydroxide 41, 139
" Iodide 140
" Nitrate 139
" Basic 139
" Oxyiodide 141
" Sulphate 143
Bismuthic Acid 142
Boracic Acid no
Borax, manufacture of 109
Boron 107
Cadmium Carbonate 94
Caesium Compounds, Prepara-
tion of 63
Calcium Carbonate 89
" Chloride . . 89
" porous 87
" Chromate 90
" Hydroxide 36
" Phosphate, crystalline. 90
" Phosphide 131
Sulphide 26
Carbon Dioxide 29
" Disulphide 177
Monoxide 28
Oxysulphide 175
Chlorine 10
Apparatus for a con-
stant supply of ... . 12
INDEX.
Chlorine
for Laboratory pur-
poses
" from Chloride of Lime, n
" Properties of 14
" Water 10
Chromium 149
Acetate 153
Chloride, Anhydrous, 151
Oxide 152
Chromyl Chloride 150
Chydrazaine 1 74
Cinnabar 104
Cobalt Nitrate 144
Copper, Ammonium Sulphate. 75
" Potassium " . 75
Gupric Sulphate 76
Cuprous Ammonium Iodide. . . 77
Chloride 73
'■' Properties of 74
Cyanide 74
Oxide 76
Phosphide 78
Cuproammonium Tetriodide. . . 78
Determination of Soluble Chlor-
ides 181
Ferric Chloride 163
" " Anhydrous. ... 164
Ferrous Bromide, Anhydrous. . 166
" Chloride .. 164
V Sulphate 166
Furnace, Roessler's 37
Gold 82
" Trichloride 83
Hydrazine 1 74
Hydrofluosilicic Acid 156
Hydrogen 9
" Arsenide 136
" " Bromide 118
" Iodide 122
" Peroxide 145
" Phosphide 133
Properties of 10
" Sodium Ammonium
Phosphate . 58
" " Sulphite ... 52
" Sulphide 25
" Arsenic
free from ... 26
PAGE.
Hydrogen Sulphide Properties
of 27
- " " Hjydrogen
Arsenide, free
from 27
Hydroxylamine 173
Hydrochloride. 173
Iodine Pentoxide 123
" Trichloride 124
Iron Ammonium Alum...... 167
Lead Carbonate 39
" Dioxide 36
" Properties of . . . 48
Tetrachloride 40
Lime 36
Lithium Normal Arsenate. ... 63
Phosphate . . 63
Magnesium, Basic Carbonate. . 87
Carbonate, crystal-
lized, normal. . 86
Chloride Anhydrous, 84
Manganese 157
Chloride 159
Oxide 160
Sulphate 16 r
Manganous Sulphide 161
Mercury 100
" Purification of 102
Mercuric Chloride 103
" Cyanide 104
Mercurous Bromide 107
Iodide 106
Nitrate 105
Methyl Orange 179, 180
Mono Calcium Phosphate Crys-
talline 90
" Sodium Phosphite 56
Nitrogen 10, 16
" Properties of 10
" Tetroxide 21
Nitric Oxide 20
Nitrous " 19
Normal Solutions 179
Oxygen 7
" Cubes 8
" Properties of 8
Phosphoric Acid 129
Phosphorus 128
INDEX.
Ill
PAGE.
Phosphorus Oxyfluoride 133
Trisulphide 131
Phenolphthalein, Solution of. . 180
Platinoso Chlorides 171
Platinum 168
Black 171
Platinic Chloride. ... 169
Potassa, Prepared with Baryta. 34
" Purified with Alcohol.. 33
Potassium Bromide 68
Chlorate 57
Chlorochromate 154
Cobaltic Oxalate. . . 62
Cyanate 60
Cyanide 50
Solution of 184
Dichromate Solution
of 182
Ferricyanide 59
Hydroxide 31
Iodide 60
Manganate 162
Metantimonate 62
Nitrite 52, 53
" Properties of, 53
Permanganate, So-
lution of 184
Peroxide 148
Pyroantimonate 54
Sulphide 43
Sulphocyanide 51
Roessler's Furnace 37
Rubidium Compounds, Prepar-
ation of . 63
Salts, Preparation of, 64
Selenium 155
Silicon no
" Chloride 113, 114, 115
Silver 79
' Potassium Carbonate 81
Silver Nitrate, Solution of . . . . 181
Sodium 46
Acetate 44
Amalgam g, 47
Ammonium Hydrogen
Phosphate 58
PAGE.
Sodium Bisulphate 58
Carbonate 48
Free from Sul-
phur and
Chlorine . . 48
Free from Sil-'
ica 48
Properties of, 49
Normal solu-
tions of. . . 179
Sodium Chloride . 45
Dioxide 7
Hydrogen Sulphite 52
Prop-
erties of 52
Hydroxide 31
Specific Grav-
ity of Solutions of. . . 33
Nitrate 56
Nitrite 53
" Peroxide 148
" Sulphide 43
Thiosulphate, Solution
of 183
Soluble Chlorides, Determin-
ation of 181
Stannic Chloride, Anhydrous.. 127
Stannous " 126
Anhydrous . 127
Strontium Hydroxide 92
Salts, Preparation of, 93
Sulphur Dichloride 148
Dioxide 27
Properties of, 28
Monochloride 148
Sulphuric Acid 1 79, 180
Sulphuric Acid values 187
Table of the Chemical Elements
with their Atomic Weights, 186
Table of Sulphuric Acid values, 187
Titanium Trioxide 65
Tungstates, Free from Molybde-
num 64
Ultramarine 117
Vanadyl Chloride 67
IV
INDEX.
PAGE.
Vanadyl Trichloride 66
Volumetric Analysis 178
Water 1
" Ammonia free 2
" Free from Organic Mat-
ter and Ammonia. . . 2
PAGE.
Water Apparatus for Preparing
free from Organic Mat-
ter and Ammonia. ... 3, 4
" Chlorine 10
Zinc free from Arsenic 91
" Eisen 92
APR 171902
APR. 24 1902
^W^ o>.W^r *n'.W; /°-;,5
Q>. ■'o.
tf- .
"77.^ J> ,, ^."77,^ # % */vv^^-#
jfV %, •
v* ^
-j>%,
^77^* #
■ ^
w /^fc^
'cp\m:
c3 **
Live Music Archive
Librivox Free Audio
Metropolitan Museum
Cleveland Museum of Art
Internet Arcade
Console Living Room
Books to Borrow
Open Library
TV News
Understanding 9/11